Enable FF_USE_FASTZIP in MR pipelines

This enables the FF_USE_FASTZIP runner feature flag to use the more
performant compression library 'fastzip' within the runner.

This is promising because we spend a significant amount of time waiting
on artifacts and caches to be (de-)compressed (and up-/downloaded). Any
improvement in performance here will compound across all jobs we run.

.gitlab-ci.yml

@@ -48,6 +48,7 @@ default:
   ADD_SLOW_TEST_NOTE_TO_MERGE_REQUEST: "true"
   FF_NETWORK_PER_BUILD: "true"
   FF_TIMESTAMPS: "true"
+  FF_USE_FASTZIP: "true"
 
 .if-merge-request-security-canonical-sync: &if-merge-request-security-canonical-sync
   if: '$CI_MERGE_REQUEST_SOURCE_PROJECT_PATH == "gitlab-org/security/gitlab" && $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME == $CI_DEFAULT_BRANCH && $CI_MERGE_REQUEST_TARGET_BRANCH_NAME == $CI_DEFAULT_BRANCH'