What is the purpose of the change

fix #5971

fix tag router select wrong provider issue
Report
XXXXX 'Provider--A with no tag, Provider--B with tag (dubbo.tag=grey)'

1. Consumer with no tag, do select get A;
2. Consumer with tag(grey), do select get B;
3. Consumer with attachment(dubbo.tag=grey), do select get B;
4. Consumer with tag(grey_), do select get A;

Verifying this change

ClusterUtils.class

Follow this checklist to help us incorporate your contribution quickly and easily:

• Make sure there is a GITHUB_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GITHUB issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [Dubbo-XXX] Fix UnknownException when host config not exist #XXX. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Run mvn clean install -DskipTests=false & mvn clean test-compile failsafe:integration-test to make sure unit-test and integration-test pass.
• If this contribution is large, please follow the Software Donation Guide.