Merge all rule validation scripts under a single task (#4255)

We shouldn't clone the whole repository three times to run three scripts that each take a few seconds.

.cirrus.yml

@@ -77,15 +77,6 @@ frontend_tests_task:
     - cd frontend
     - sonar-scanner
 
-validate_metadata_task:
-  eks_container:
-    <<: *CONTAINER_DEFINITION
-    dockerfile: ci/Dockerfile
-    cpu: 1
-    memory: 2G
-  metadata_tests_script:
-    - ./ci/validate_metadata.sh
-
 validate_ci_tests_task:
   skip: "!changesInclude('ci_tests/**', 'ci/**')"
   eks_container:
@@ -96,13 +87,17 @@ validate_ci_tests_task:
   ci_tests_script:
     - ./ci_tests/asciidoc_validation/run_tests.sh
 
-validate_asciidoc_task:
+validate_rules_task:
   eks_container:
     <<: *CONTAINER_DEFINITION
     dockerfile: ci/Dockerfile
     cpu: 1
     memory: 2G
-  asciidoc_tests_script:
+  metadata_validation_script:
+    - ./ci/validate_metadata.sh
+  file_extensions_validation_script:
+    - ./ci/validate_file_extensions.sh
+  asciidoc_validation_script:
     - ./ci/validate_asciidoc.sh
 
 validate_links_task:
@@ -126,23 +121,12 @@ validate_links_task:
       - md5sum /root/link-probing-history.cache/link_probes.history || true
       - bash ci/cirrus-cache.sh upload ${LINK_CACHE_NAME} ${LINK_CACHE_PATH}
 
-validate_file_extensions_task:
-  eks_container:
-    <<: *CONTAINER_DEFINITION
-    dockerfile: ci/Dockerfile
-    cpu: 1
-    memory: 2G
-  file_extension_tests_script:
-    - bash ./ci/validate_file_extensions.sh
-
 all_required_checks_task:
   depends_on:
     - tooling_tests
     - frontend_tests
-    - validate_metadata
-    - validate_asciidoc
+    - validate_rules
     - validate_ci_tests
-    - validate_file_extensions
   eks_container:
     <<: *CONTAINER_DEFINITION
     dockerfile: ci/Dockerfile