Previously, removeIncludeIfCredentials() deleted all includeIf.gitdir
entries matching git-credentials-*.config, regardless of which action
created them. This broke subsequent workflow steps that relied on
credentials persisted by other actions (e.g., actions/checkout@v6).
Now the cleanup only removes the specific credentials file and config
entries created by this action instance, leaving other actions'
credentials intact.
ca2f66fc96