Collapse secret_detection jobs into a single job

Moves the logic from secret_detection_default_branch into
the secret_deteciton job.
Changelog: changed

lib/gitlab/ci/templates/Jobs/Secret-Detection.gitlab-ci.yml

 # Read more about this feature here: https://docs.gitlab.com/ee/user/application_security/secret_detection
 #
-# Configure secret detection with CI/CD variables (https://docs.gitlab.com/ee/ci/variables/README.html).
-# List of available variables: https://docs.gitlab.com/ee/user/application_security/secret_detection/#available-variables
+# Configure the scanning tool through the environment variables.
+# List of the variables: https://docs.gitlab.com/ee/user/application_security/secret_detection/#available-variables
+# How to set: https://docs.gitlab.com/ee/ci/yaml/#variables
 
 variables:
   SECURE_ANALYZERS_PREFIX: "registry.gitlab.com/gitlab-org/security-products/analyzers"
   SECRETS_ANALYZER_VERSION: "3"
   SECRET_DETECTION_EXCLUDED_PATHS: ""
 
-
 .secret-analyzer:
   stage: test
   image: "$SECURE_ANALYZERS_PREFIX/secrets:$SECRETS_ANALYZER_VERSION"
@@ -20,23 +20,15 @@ variables:
     reports:
       secret_detection: gl-secret-detection-report.json
 
-secret_detection_default_branch:
-  extends: .secret-analyzer
-  rules:
-    - if: $SECRET_DETECTION_DISABLED
-      when: never
-    - if: $CI_DEFAULT_BRANCH == $CI_COMMIT_BRANCH
-  script:
-    - /analyzer run
-
 secret_detection:
   extends: .secret-analyzer
   rules:
     - if: $SECRET_DETECTION_DISABLED
       when: never
-    - if: $CI_COMMIT_BRANCH && $CI_COMMIT_BRANCH != $CI_DEFAULT_BRANCH
+    - if: $CI_COMMIT_BRANCH
   script:
     - if [[ $CI_COMMIT_TAG ]]; then echo "Skipping Secret Detection for tags. No code changes have occurred."; exit 0; fi
+    - if [[ $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH ]]; then echo "Running Secret Detection on default branch."; /analyzer run; exit 0; fi
     - git fetch origin $CI_DEFAULT_BRANCH $CI_COMMIT_REF_NAME
     - git log --left-right --cherry-pick --pretty=format:"%H" refs/remotes/origin/$CI_DEFAULT_BRANCH...refs/remotes/origin/$CI_COMMIT_REF_NAME > "$CI_COMMIT_SHA"_commit_list.txt
     - export SECRET_DETECTION_COMMITS_FILE="$CI_COMMIT_SHA"_commit_list.txt

spec/services/ci/create_pipeline_service_spec.rb

@@ -533,7 +533,7 @@ RSpec.describe Ci::CreatePipelineService do
         it 'pull it from Auto-DevOps' do
           pipeline = execute_service
           expect(pipeline).to be_auto_devops_source
-          expect(pipeline.builds.map(&:name)).to match_array(%w[brakeman-sast build code_quality eslint-sast secret_detection_default_branch semgrep-sast test])
+          expect(pipeline.builds.map(&:name)).to match_array(%w[brakeman-sast build code_quality eslint-sast secret_detection semgrep-sast test])
         end
       end