Adopt the official D11 testing using `OPT_IN_TEST_NEXT_MAJOR` (thanks to...

Adopt the official D11 testing using `OPT_IN_TEST_NEXT_MAJOR` (thanks to https://www.drupal.org/project/gitlab_templates/issues/3396106).

.gitlab-ci.yml

@@ -30,6 +30,8 @@ include:
 ################
 variables:
   SKIP_ESLINT: '1'
+  # Opt in to testing $CORE_MAJOR_DEVELOPMENT (currently Drupal 11).
+  OPT_IN_TEST_NEXT_MAJOR: '1'
 
 composer:
   parallel:
@@ -43,11 +45,9 @@ composer:
           - $CORE_SECURITY_PREVIOUS_MINOR
           - $CORE_STABLE
           - $CORE_NEXT_MINOR
-      # Drupal 10 (max PHP) & 11.
+      # Drupal 10 (max PHP).
       - _TARGET_PHP: [$CORE_PHP_MAX]
-        _TARGET_CORE:
-          - $CORE_STABLE
-          - $CORE_MAJOR_DEVELOPMENT
+        _TARGET_CORE: [$CORE_STABLE]
 
 phpcs:
   # Set allow_failure to false so that the test fails for coding standards faults.
@@ -108,17 +108,3 @@ phpunit (next minor):
         matrix:
           - _TARGET_PHP: $CORE_PHP_MIN
             _TARGET_CORE: $CORE_NEXT_MINOR
-phpunit (next major):
-  allow_failure: true
-  extends: phpunit
-  needs:
-    - job: composer
-      parallel:
-        matrix:
-          - _TARGET_PHP: $CORE_PHP_MAX
-            _TARGET_CORE: $CORE_MAJOR_DEVELOPMENT
-  before_script:
-    # If the module already supports Drupal 11, do nothing, otherwise, claim Drupal 11 support for testing purposes.
-    - grep -q "\^11" *.info.yml || (grep -q "\^10" *.info.yml && sed -i "s/\^10/\^10 \|\| ^11/" *.info.yml)
-  variables:
-    _TARGET_PHP: $CORE_PHP_MAX