Migrate GlDropdown in toolbar_more_dropdown.vue to GlDisclosure

What does this MR do and why?

Migrate GlDropdown in app/assets/javascripts/content_editor/components/toolbar_more_dropdown.vue to GlDisclosure

Closes #384293 (closed)

Screenshots or screen recordings

Before:

After:

How to set up and validate locally

Apply the patch below to force the component to show, and test the component on a content editor (e.g. Issues description)

diff --git a/app/assets/javascripts/issues/show/components/fields/description.vue b/app/assets/javascripts/issues/show/components/fields/description.vue
index 04c5007dbec6..2fbadf4a5745 100644
--- a/app/assets/javascripts/issues/show/components/fields/description.vue
+++ b/app/assets/javascripts/issues/show/components/fields/description.vue
@@ -55,7 +55,7 @@ export default {
   <div class="common-note-form">
     <label class="sr-only" for="issue-description">{{ __('Description') }}</label>
     <markdown-editor
-      v-if="glFeatures.contentEditorOnIssues"
+      v-if="true"
       class="gl-mt-3"
       :value="value"
       :render-markdown-path="markdownPreviewPath"
diff --git a/app/assets/javascripts/vue_shared/components/markdown/markdown_editor.vue b/app/assets/javascripts/vue_shared/components/markdown/markdown_editor.vue
index c53118b9f621..1a5998cef114 100644
--- a/app/assets/javascripts/vue_shared/components/markdown/markdown_editor.vue
+++ b/app/assets/javascripts/vue_shared/components/markdown/markdown_editor.vue
@@ -1,7 +1,7 @@
 <script>
 import axios from '~/lib/utils/axios_utils';
 import LocalStorageSync from '~/vue_shared/components/local_storage_sync.vue';
-import { EDITING_MODE_MARKDOWN_FIELD, EDITING_MODE_CONTENT_EDITOR } from '../../constants';
+import { EDITING_MODE_MARKDOWN_FIELD } from '../../constants';
 import MarkdownField from './field.vue';
 
 export default {
@@ -93,7 +93,7 @@ export default {
   },
   computed: {
     isContentEditorActive() {
-      return this.enableContentEditor && this.editingMode === EDITING_MODE_CONTENT_EDITOR;
+      return true;
     },
     contentEditorAutofocused() {
       // Match textarea focus behavior

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.