Enable pointer events in tooltips

Tooltips were non-interactible because pointer
events were disabled

app/assets/javascripts/boards/components/boards_selector.vue

@@ -261,7 +261,7 @@ export default {
         >
           <gl-deprecated-dropdown-item
             v-show="filteredBoards.length === 0"
-            class="no-pointer-events text-secondary"
+            class="gl-pointer-events-none text-secondary"
           >
             {{ s__('IssueBoards|No matching boards found') }}
           </gl-deprecated-dropdown-item>

app/assets/javascripts/pipelines/components/pipelines_list/stage.vue

@@ -168,7 +168,7 @@ export default {
       aria-expanded="false"
       @click="onClickStage"
     >
-      <span :aria-label="stage.title" aria-hidden="true" class="no-pointer-events">
+      <span :aria-label="stage.title" aria-hidden="true" class="gl-pointer-events-none">
         <gl-icon :name="borderlessIcon" />
       </span>
     </button>

app/assets/stylesheets/bootstrap_migration.scss

@@ -131,12 +131,6 @@ table {
   border-spacing: 0;
 }
 
-.tooltip,
-.no-pointer-events {
-  // Fix bootstrap4 bug whereby tooltips flicker when they are hovered over their borders
-  pointer-events: none;
-}
-
 @each $breakpoint in map-keys($grid-breakpoints) {
   @include media-breakpoint-up($breakpoint) {
     $infix: breakpoint-infix($breakpoint, $grid-breakpoints);