Remove hover utilities in favor of @gitlab/ui

- Remove temp utility.
- Use gitlab/ui utility classes.
- Remove unneeded flexbox utilities.
- Match icon margin with the task status element.

app/assets/stylesheets/utilities.scss

@@ -14,12 +14,6 @@
     #{'.text-#{$variant}-#{$suffix}'} {
       color: $color;
     }
-
-    #{'.hover-text-#{$variant}-#{$suffix}'} {
-      &:hover {
-        color: $color;
-      }
-    }
   }
 }
 

app/views/projects/issues/_issue.html.haml

@@ -6,7 +6,7 @@
         = check_box_tag dom_id(issue, "selected"), nil, false, 'data-id' => issue.id, class: "selected-issuable"
     .issuable-info-container
       .issuable-main-info
-        .issue-title.title.d-flex.align-items-center
+        .issue-title.title
           %span.issue-title-text.js-onboarding-issue-item{ dir: "auto" }
             - if issue.confidential?
               %span.has-tooltip{ title: _('Confidential') }

ee/app/views/projects/issues/_subepic_flag.html.haml

 - return unless issue_in_subepic?(issue, params[:epic_id])
 
-%span.d-inline-block.ml-1{ title: _('This issue is in a child epic of the filtered epic'), data: { toggle: 'tooltip', container: 'body' } }
-  = sprite_icon('information-o', css_class: 'd-block text-primary-500 hover-text-primary-800')
+%span.gl-display-inline-block.gl-ml-2{ title: _('This issue is in a child epic of the filtered epic'), data: { toggle: 'tooltip', container: 'body' } }
+  = sprite_icon('information-o', css_class: 'gl-text-blue-500 gl-hover-text-blue-800')