Merge branch '5426-fe-web-terminal-empty-state-ce' into 'master'

CE Port2 of "Add empty and disabled web terminal tab"

See merge request gitlab-org/gitlab-ce!23509

app/assets/stylesheets/framework.scss

@@ -6,7 +6,6 @@
 @import 'bootstrap_migration';
 @import 'framework/layout';
 
-@import 'framework/alerts';
 @import 'framework/animations';
 @import 'framework/vue_transitions';
 @import 'framework/avatar';

app/assets/stylesheets/framework/alerts.scss

-.alert-tip {
-  background-color: $theme-gray-100;
-  color: $theme-gray-900;
-}