pull requests updating module_utils: path components which are existing labels are not automatically added

[pilou-]

When a pull request updates a module_utils file, if there is a related entry in .github/BOTMETA.yml then path components which are valid GitHub labels are automatically added.

Applying the same behavior for pull requests without an entry in .github/BOTMETA.yml would improve triage. Use cases:

• to identify pull requests related to a subject (for example: when looking if a pull request already exists)
• maintainers looking for pull requests related to a specific component