[Meta] Prepare for D9

Add a patch for Drupal CI with following and look for all the errors, create separate issues for them and fix. Once no issues left, commit the config file to ensure all future changes are verified.

@see: https://www.drupal.org/node/3032484 for more details.

build:
  assessment:
    validate_codebase:
      # Static analysis of code for @deprecated uses.
      phpstan:
        halt-on-fail: false
    testing:
      run_tests.standard:
        types: 'Simpletest,PHPUnit-Unit,PHPUnit-Kernel,PHPUnit-Functional'
        # Fails on errors triggered.
        suppress-deprecations: false
      run_tests.js:
        concurrency: 1
        types: 'PHPUnit-FunctionalJavascript'
        # Fails on errors triggered.
        suppress-deprecations: false