Feature/versioned mess detector

[kapilpandya22]

Summary

• Updates the reusable mess-detector workflow to use the new PHP version-specific action
• Aligns with the existing pattern used by coding-standard.yml and phpstan.yml which already pin to a specific PHP version
• PHP 8.5 is used as the single version — PHPMD is a static analysis tool checking code quality rules, not PHP runtime compatibility, so
  a matrix is not needed

Dependency

This PR depends on extdn/github-actions-m2#165 (add versioned mess-detector support) being merged first. Do not
merge until that PR is live on extdn/github-actions-m2@master.

Before / After

	Before	After
Action ref	extdn/github-actions-m2/magento-mess-detector@master	extdn/github-actions-m2/magento-mess-detector/8.5@master
PHP version	Unspecified (baked into single image)	Explicit PHP 8.5
Pattern	Inconsistent with other static analysis workflows	Consistent with coding-standard and phpstan