…ccountKeys twice" (#20427)

This PR fails in CDK v2 because the added unit tests that use `testFutureBehavior` fail on the CDK v2 branch. I believe they're failing because the `testFutureBehavior` utility function was written before CDK v2 was released, and so it automatically discards all feature flags - which should not be happening for new feature flags. I'm not sure what the best fix for this is so I'm just reverting it for the time being to unblock the release.

Test logs:
<details>

```
FAIL test/pipeline.test.js (12.04 s)
  ●  › cross account key alias name tests › cross account key alias is named with stack name instead of ID when feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-pipelinestackpipeline9db740af",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "PipelineArtifactsBucketEncryptionKey01D58D69",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-name-pipeline-0a412eb5 but received alias/codepipeline-pipelinestackpipeline9db740af at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:500:33)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias is named with generated stack name when stack name is undefined and feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-pipelinestackpipeline9db740af",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "PipelineArtifactsBucketEncryptionKey01D58D69",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-pipelinestack-pipeline-9db740af but received alias/codepipeline-pipelinestackpipeline9db740af at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:525:33)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias is named with stack name and nested stack ID when feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-toplevelstacknestedpipelinestackactualpipeline3161a537",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "ActualPipelineArtifactsBucketEncryptionKeyDF448A3D",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-name-nestedpipelinestack-actualpipeline-23a98110 but received alias/codepipeline-toplevelstacknestedpipelinestackactualpipeline3161a537 at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:552:46)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias is named with generated stack name and nested stack ID when stack name is undefined and feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-toplevelstacknestedpipelinestackactualpipeline3161a537",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "ActualPipelineArtifactsBucketEncryptionKeyDF448A3D",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-toplevelstack-nestedpipelinestack-actualpipeline-3161a537 but received alias/codepipeline-toplevelstacknestedpipelinestackactualpipeline3161a537 at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:581:46)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias is properly shortened to 256 characters when stack name is too long and feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-toolongactualpipelinewithextrasuperlongnamethatwillneedtobeshortenedduetothealsoverysuperextralongnameofthestackalsowithsomedifferentcharactersaddedtotheendc9bb503e",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "ActualPipelineWithExtraSuperLongNameThatWillNeedToBeShortenedDueToTheAlsoVerySuperExtraLongNameOfTheStackAlsoWithSomeDifferentCharactersAddedToTheEndArtifactsBucketEncryptionKeyABD1BD7F",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-needstobeshortenedduetothelengthofthisabsurdnamethatnooneshouldusebutitstillmighthappensowemusttestfohatwillneedtobeshortenedduetothealsoverysuperextralongnameofthestack-alsowithsomedifferentcharactersaddedtotheend-384b9343 but received alias/codepipeline-toolongactualpipelinewithextrasuperlongnamethatwillneedtobeshortenedduetothealsoverysuperextralongnameofthestackalsowithsomedifferentcharactersaddedtotheendc9bb503e at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:609:33)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias names do not conflict when the stack ID is the same and pipeline ID is the same and feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-stackidpipeline32fb88b3",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "PipelineArtifactsBucketEncryptionKey01D58D69",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-1-pipeline-b09fefee but received alias/codepipeline-stackidpipeline32fb88b3 at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:643:34)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias names do not conflict for nested stacks when pipeline ID is the same and nested stacks have the same ID when feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-stackidnestedpipelineid3e91360a",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "PIPELINEIDArtifactsBucketEncryptionKeyE292C50C",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-name-1-nested-pipeline-id-c8c9f252 but received alias/codepipeline-stackidnestedpipelineid3e91360a at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:697:47)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)

  ●  › cross account key alias name tests › cross account key alias names do not conflict for nested stacks when in the same stack but nested stacks have different IDs when feature flag is enabled

    Template has 1 resources with type AWS::KMS::Alias, but none match as expected.
    The closest result is:
      {
        "Type": "AWS::KMS::Alias",
        "Properties": {
          "AliasName": "alias/codepipeline-stackidfirstpipelineid5abca693",
          "TargetKeyId": {
            "Fn::GetAtt": [
              "PIPELINEIDArtifactsBucketEncryptionKeyE292C50C",
              "Arn"
            ]
          }
        },
        "UpdateReplacePolicy": "Delete",
        "DeletionPolicy": "Delete"
      }
    with the following mismatches:
    	Expected alias/codepipeline-actual-stack-name-1-first-pipeline-id-3c59cb88 but received alias/codepipeline-stackidfirstpipelineid5abca693 at /Properties/AliasName (using objectLike matcher)

      83 |     const matchError = hasResourceProperties(this.template, type, props);
      84 |     if (matchError) {
    > 85 |       throw new Error(matchError);
         |             ^
      86 |     }
      87 |   }
      88 |

      at Template.hasResourceProperties (../assertions/lib/template.ts:85:13)
      at fn (test/pipeline.test.ts:749:46)
      at Object.<anonymous> (../../../tools/@aws-cdk/cdk-build-tools/lib/feature-flag.ts:34:35)
```

</details>

----

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