Relates #2285

At least, system tests are failing in cef package due to a type set in the mapping for url.original different from ECS.

That mapping comes from the dynamic templates created with the import_mappings setting.

This PR tries to solve this error in cef package by updating the ECS mappings that elastic-package adds automatically via the import_mappings setting.

Currently, the embedded dynamic template created by elastic-package when import_mappings is enabled does not take any effect (it does not match path_match):

        {
          "_embedded_ecs-url_original_to_multifield": {
            "path_match": "*.url.original",
            "mapping": {
              "fields": {
                "text": {
                  "type": "match_only_text"
                }
              },
              "type": "wildcard"
            }
          }
        },

The goal of this PR is to update that dynamic template to be as similar as possible to the ecs@mappings component template (without unmatch_mapping_type parameter since it is not supported in 8.6.x):

        {
          "ecs_path_match_wildcard_and_match_only_text": {
            "path_match": [
              "*.body.content",
              "*url.full",
              "*url.original"
            ],
            "unmatch_mapping_type": "object",
            "mapping": {
              "fields": {
                "text": {
                  "type": "match_only_text"
                }
              },
              "type": "wildcard"
            }
          }
        },

This PR has been tested:

• Test packages of integrations repository with current validation based on fields
  • https://buildkite.com/elastic/integrations/builds/20364
• Test packages of integrations repository with the validation based on mappings (including latest changes in Validate fields based on their mappings and the dynamic templates set #2285)
  • https://buildkite.com/elastic/integrations/builds/20366