Remove mr_comment_neighbor_nav flag

Remove feature flag added in
  https://gitlab.com/gitlab-org/gitlab/-/merge_requests/28596

app/assets/javascripts/diffs/components/app.vue

@@ -425,7 +425,7 @@ export default {
         }
       });
 
-      if (this.commit && this.glFeatures.mrCommitNeighborNav) {
+      if (this.commit) {
         Mousetrap.bind('c', () => this.moveToNeighboringCommit({ direction: 'next' }));
         Mousetrap.bind('x', () => this.moveToNeighboringCommit({ direction: 'previous' }));
       }

app/assets/javascripts/diffs/components/commit_item.vue

@@ -148,10 +148,7 @@ export default {
             class="input-group-text"
           />
         </gl-button-group>
-        <div
-          v-if="hasNeighborCommits && glFeatures.mrCommitNeighborNav"
-          class="commit-nav-buttons ml-3"
-        >
+        <div v-if="hasNeighborCommits" class="commit-nav-buttons ml-3">
           <gl-button-group>
             <gl-button
               :href="previousCommitUrl"

app/controllers/projects/merge_requests_controller.rb

@@ -28,7 +28,6 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
   before_action :authenticate_user!, only: [:assign_related_issues]
   before_action :check_user_can_push_to_source_branch!, only: [:rebase]
   before_action only: [:show] do
-    push_frontend_feature_flag(:mr_commit_neighbor_nav, @project, default_enabled: true)
     push_frontend_feature_flag(:multiline_comments, @project, default_enabled: true)
     push_frontend_feature_flag(:file_identifier_hash)
     push_frontend_feature_flag(:batch_suggestions, @project, default_enabled: true)

config/feature_flags/development/mr_commit_neighbor_nav.yml

----
-name: mr_commit_neighbor_nav
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/28596
-rollout_issue_url: 
-milestone: '13.0'
-type: development
-group: group::code review
-default_enabled: true

spec/frontend/diffs/components/app_spec.js

@@ -288,7 +288,7 @@ describe('diffs/components/app', () => {
         ({ state }) => {
           state.diffs.commit = { id: 'SHA123' };
         },
-        { glFeatures: { mrCommitNeighborNav: true, ...featureFlags } },
+        { glFeatures: featureFlags },
       );
 
       moveSpy = jest.spyOn(wrapper.vm, 'moveToNeighboringCommit').mockImplementation(() => {});
@@ -303,8 +303,8 @@ describe('diffs/components/app', () => {
         ${'k'} | ${'jumpToFile'}              | ${0} | ${[-1]}                        | ${{}}
         ${']'} | ${'jumpToFile'}              | ${0} | ${[+1]}                        | ${{}}
         ${'j'} | ${'jumpToFile'}              | ${0} | ${[+1]}                        | ${{}}
-        ${'x'} | ${'moveToNeighboringCommit'} | ${1} | ${[{ direction: 'previous' }]} | ${{ mrCommitNeighborNav: true }}
-        ${'c'} | ${'moveToNeighboringCommit'} | ${1} | ${[{ direction: 'next' }]}     | ${{ mrCommitNeighborNav: true }}
+        ${'x'} | ${'moveToNeighboringCommit'} | ${1} | ${[{ direction: 'previous' }]} | ${{}}
+        ${'c'} | ${'moveToNeighboringCommit'} | ${1} | ${[{ direction: 'next' }]}     | ${{}}
       `(
         'calls `$name()` with correct parameters whenever the "$key" key is pressed',
         async ({ key, spy, args, featureFlags }) => {
@@ -319,24 +319,6 @@ describe('diffs/components/app', () => {
         },
       );
 
-      it.each`
-        key    | name                         | spy  | featureFlags
-        ${'x'} | ${'moveToNeighboringCommit'} | ${1} | ${{ mrCommitNeighborNav: false }}
-        ${'c'} | ${'moveToNeighboringCommit'} | ${1} | ${{ mrCommitNeighborNav: false }}
-      `(
-        'does not call `$name()` even when the correct key is pressed if the feature flag is disabled',
-        async ({ key, spy, featureFlags }) => {
-          setup({ shouldShow: true }, featureFlags);
-
-          await nextTick();
-          expect(spies[spy]).not.toHaveBeenCalled();
-
-          Mousetrap.trigger(key);
-
-          expect(spies[spy]).not.toHaveBeenCalled();
-        },
-      );
-
       it.each`
         key    | name                         | spy  | allowed
         ${'d'} | ${'jumpToFile'}              | ${0} | ${['[', ']', 'j', 'k']}
@@ -344,7 +326,7 @@ describe('diffs/components/app', () => {
       `(
         `does not call \`$name()\` when a key that is not one of \`$allowed\` is pressed`,
         async ({ key, spy }) => {
-          setup({ shouldShow: true }, { mrCommitNeighborNav: true });
+          setup({ shouldShow: true });
 
           await nextTick();
           Mousetrap.trigger(key);
@@ -356,7 +338,7 @@ describe('diffs/components/app', () => {
 
     describe('hidden app', () => {
       beforeEach(async () => {
-        setup({ shouldShow: false }, { mrCommitNeighborNav: true });
+        setup({ shouldShow: false });
 
         await nextTick();
         Mousetrap.reset();

spec/frontend/diffs/components/commit_item_spec.js

@@ -44,10 +44,7 @@ describe('diffs/components/commit_item', () => {
         ...propsData,
       },
       provide: {
-        glFeatures: {
-          mrCommitNeighborNav: true,
-          ...featureFlags,
-        },
+        glFeatures: featureFlags,
       },
       stubs: {
         CommitPipelineStatus: true,
@@ -224,12 +221,6 @@ describe('diffs/components/commit_item', () => {
       expect(getCommitNavButtonsElement().exists()).toEqual(true);
     });
 
-    it('does not render the commit navigation buttons if the `mrCommitNeighborNav` feature flag is disabled', () => {
-      mountComponent({ commit: mrCommit }, { mrCommitNeighborNav: false });
-
-      expect(getCommitNavButtonsElement().exists()).toEqual(false);
-    });
-
     describe('prev commit', () => {
       const { location } = window;