Add unbind hook to SafeHtml directive

What does this MR do and why?

This adds unbind hook to GlSafeHtmlDirective to fix potential memory leaks when used with other components like GlModal.

This has already been updated in gitlab-org/gitlab project: gitlab!139561 (merged)

Screenshots or screen recordings

No visual changes

How to set up and validate locally

1. Create a modal and add content with a div and a GlSafeHtml directive on it:

Sample Patch

diff --git a/ee/app/assets/javascripts/on_demand_scans/components/empty_state.vue b/ee/app/assets/javascripts/on_demand_scans/components/empty_state.vue
index a1d925341ff2..7c6aaef0a811 100644
--- a/ee/app/assets/javascripts/on_demand_scans/components/empty_state.vue
+++ b/ee/app/assets/javascripts/on_demand_scans/components/empty_state.vue
@@ -1,5 +1,14 @@
 <script>
-import { GlEmptyState, GlSprintf, GlLink } from '@gitlab/ui';
+import {
+  GlEmptyState,
+  GlSprintf,
+  GlLink,
+  GlModal,
+  GlButton,
+  GlModalDirective,
+
+} from '@gitlab/ui';
+import SafeHtml from '~/vue_shared/directives/safe_html';
 import { s__ } from '~/locale';
 import { HELP_PAGE_PATH } from '../constants';
 
@@ -9,6 +18,12 @@ export default {
     GlEmptyState,
     GlSprintf,
     GlLink,
+    GlModal,
+    GlButton,
+  },
+  directives: {
+    SafeHtml,
+    GlModal: GlModalDirective,
   },
   inject: ['newDastScanPath', 'emptyStateSvgPath'],
   props: {
@@ -30,6 +45,11 @@ export default {
       default: false,
     },
   },
+  data() {
+    return {
+      modalId: 'testmodal',
+    };
+  },
   computed: {
     emptyStateProps() {
       const props = {
@@ -44,21 +64,32 @@ export default {
 
       return props;
     },
+    html() {
+      return '<a class="qwerty" href="https://google.com">hello</a>';
+    },
   },
   i18n: {
     primaryButtonText: s__('OnDemandScans|New scan'),
   },
+  methods: {
+    openModal() {
+      this.$refs.modal.show();
+    },
+    onCancel() {
+      this.$refs.modal.hide();
+    },
+  },
 };
 </script>
 
 <template>
-  <gl-empty-state v-bind="emptyStateProps" :svg-height="144">
-    <template #description>
-      <gl-sprintf :message="text">
-        <template #learnMoreLink="{ content }">
-          <gl-link :href="$options.HELP_PAGE_PATH">{{ content }}</gl-link>
-        </template>
-      </gl-sprintf>
-    </template>
-  </gl-empty-state>
+  <div>
+    <gl-button v-gl-modal="modalId" category="secondary"> Open </gl-button>
+    <gl-modal ref="modal" :modal-id="modalId">
+      <div v-safe-html="html"></div>
+      <template #modal-footer>
+        <gl-button category="secondary" @click="onCancel">{{ __('Cancel') }}</gl-button>
+      </template>
+    </gl-modal>
+  </div>
 </template>

2. Open and close modal several times then open developer tools, go to Memory tab and search for detached elements.

What does this MR do?

Screenshots or screen recordings

Integration merge requests

• GitLab: mr_url
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• Status Page: mr_url

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• Added the ~"component:*" label(s) if applicable.

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Accessibility

If this MR adds or modifies a component, take a few moments to review the following:

• All actions and functionality can be done with a keyboard.
• Links, buttons, and controls have a visible focus state.
• All content is presented in text or with a text equivalent. For example, alt text for SVG, or aria-label for icons that have meaning or perform actions.
• Changes in a component’s state are announced by a screen reader. For example, changing aria-expanded="false" to aria-expanded="true" when an accordion is expanded.
• Color combinations have sufficient contrast.