fix: check if label matchers have changed before composing

[thisisnithin]

Motivation and Context

Fixes unnecessary compositions when the federated graph label matchers remain unchanged.

Fixes ENG-6270

Checklist

• I have discussed my proposed changes in an issue and have received approval to proceed.
• I have followed the coding standards of the project.
• Tests or benchmarks have been added or updated.
• Documentation has been updated on https://github.com/wundergraph/cosmo-docs.
• I have read the Contributors Guide.

[StarpTech]

LGTM