Fix double colon

.gitlab-ci.yml

@@ -73,15 +73,14 @@ default:
 # Stage: build
 # ============
 #
-# Builds or updates CI test container image
+# Builds CI test container image
 # There are 2 moments in which we (re)build the container image. If some files are
-# changed, or when it needs to be done manually. There is no *or* in "only" or
-# "rules", so we have two jobs with different rules instead. Write
-# "REBUILD_CONTAINER" in your commit message to force rebuilding the container.
+# changed, or when it needs to be done manually
+# Write "REBUILD_CONTAINER" in your commit message to force rebuilding the container.
 
-ci-test-image-update:
+ci-test-image-build:
   <<: *image_build_template
-  rules::
+  rules:
     # Automatically rebuild the container image if this file, the Dockerfile,
     # the installed requirements or the kaniko template change
     - changes: