fix(manager/gitlabci): support multi-line !reference tags (#21896)

lib/modules/manager/gitlabci/__fixtures__/gitlab-ci.reference.yaml

+test:
+  script:
+    - !reference [.setup, script]
+    - !reference [arbitrary job name with space and no starting dot, nested1, nested2, nested3]
+    - !reference [
+      .multiline,
+      reference,
+    ]
+    - !reference [
+        .another, multilineref
+      ]

lib/modules/manager/gitlabci/utils.spec.ts

+import { Fixtures } from '../../../../test/fixtures';
 import type { PackageDependency } from '../types';
-import { getGitlabDep } from './utils';
+import { getGitlabDep, replaceReferenceTags } from './utils';
 
 describe('modules/manager/gitlabci/utils', () => {
   describe('getGitlabDep', () => {
@@ -81,4 +82,12 @@ describe('modules/manager/gitlabci/utils', () => {
       });
     });
   });
+
+  describe('replaceReferenceTags', () => {
+    it('replaces all !reference tags with empty strings', () => {
+      const yamlFileReferenceConfig = Fixtures.get('gitlab-ci.reference.yaml');
+      const replaced = replaceReferenceTags(yamlFileReferenceConfig);
+      expect(replaced).not.toContain('!reference');
+    });
+  });
 });

lib/modules/manager/gitlabci/utils.ts

@@ -2,7 +2,7 @@ import { regEx } from '../../../util/regex';
 import { getDep } from '../dockerfile/extract';
 import type { PackageDependency } from '../types';
 
-const re = /!reference \[(.*?)\]/g;
+const re = /!reference \[[^\]]+\]/g;
 
 /**
  * Replaces GitLab reference tags before parsing, because our yaml parser cannot process them anyway.