fix: Resolve the PHPStan findings raised by the updated analyzers

Problem/Motivation

The phpstan CI job fails on the 10.2.x and 10.0.x branches: the updated phpstan-drupal analyzers raise drupal.symfonyYamlParse in includes/updates/v10-0.inc and drupal.proceduralHookEntityOperationMissingCacheabilityParameter in varbase_layout_builder.module, both on pre-existing code.

Steps to reproduce

Run the phpstan job on the branch pipeline.

Proposed resolution

• Use \Drupal\Component\Serialization\Yaml::decode() instead of the Symfony YAML parser.
• Add the cacheability parameter to hook_entity_operation() and record the user-permissions cache context on it.

Remaining tasks

• ✅ File an issue
• ❌ Addition/Change/Update/Fix
• ❌ Testing to ensure no regression
• ➖ Automated unit testing coverage
• ➖ Automated functional testing coverage
• ➖ UX/UI designer responsibilities
• ❌ Readability
• ➖ Accessibility
• ➖ Performance
• ➖ Security
• ➖ Developer Documentation
• ➖ User Guide Documentation
• ➖ Reviewed by human
• ➖ Code review by maintainers
• ➖ Full testing and approval
• ➖ Credit contributors
• ➖ Review with the product owner
• ➖ Release notes snippet
• ✅ Release

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Modernized the YAML handling and the entity-operation hook to the updated Drupal core APIs.

AI-Generated: Yes