Merge branch 'ensure_cache_clear_after_db_migrate' into 'master'

Ensure cache clear runs after db:migrations.

Fixes #959 

Long explanation on how and why is starting with comment in https://gitlab.com/gitlab-org/omnibus-gitlab/issues/959#note_3170934

See merge request !598

files/gitlab-cookbooks/gitlab/definitions/migrate_database.rb

@@ -26,6 +26,7 @@ define :migrate_database, :command => nil, :action => :run, :restarts => [] do
       exit ${PIPESTATUS[0]}
     EOH
     action params[:action]
+    notifies :run, "execute[clear the #{params[:name]} cache]", :immediately unless OmnibusHelper.not_listening?("redis")
     params[:restarts].each do |svc|
       notifies :restart, svc, :immediately
     end

files/gitlab-cookbooks/gitlab/recipes/database_migrations.rb

@@ -42,9 +42,3 @@ migrate_database 'gitlab-rails' do
   action :nothing
   restarts dependent_services
 end
-
-migrate_database 'gitlab-ci' do
-  command '/opt/gitlab/bin/gitlab-ci-rake db:migrate'
-  action :nothing
-  restarts ci_dependent_services
-end