Rename ruby coverage job to rspec:coverage

This is to give a more indicative name that the job is for gathering
coverage for rspec. This will be used later on for code coverage graph.

.gitlab/ci/pages.gitlab-ci.yml

@@ -5,7 +5,7 @@ pages:
     - .default-cache
     - .pages:rules
   stage: pages
-  dependencies: ["coverage", "karma", "gitlab:assets:compile pull-cache"]
+  dependencies: ["rspec:coverage", "karma", "gitlab:assets:compile pull-cache"]
   script:
     - mv public/ .public/
     - mkdir public/

.gitlab/ci/rails.gitlab-ci.yml

@@ -202,7 +202,7 @@ gitlab:setup:
     paths:
       - log/development.log
 
-coverage:
+rspec:coverage:
   extends:
     - .rails-job-base
     - .rails:rules:ee-and-foss