Removed :monaco_ci flag

Removed all instances and conditions for the flag from both
HAML and JS files.

app/assets/javascripts/pages/projects/ci/lints/ci_lint_editor.js

-import createFlash from '~/flash';
-import { BLOB_EDITOR_ERROR } from '~/blob_edit/constants';
+import EditorLite from '~/editor/editor_lite';
 
 export default class CILintEditor {
   constructor() {
-    const monacoEnabled = window?.gon?.features?.monacoCi;
     this.clearYml = document.querySelector('.clear-yml');
     this.clearYml.addEventListener('click', this.clear.bind(this));
 
-    return monacoEnabled ? this.initEditorLite() : this.initAce();
+    return this.initEditorLite();
   }
 
   clear() {
@@ -15,8 +13,6 @@ export default class CILintEditor {
   }
 
   initEditorLite() {
-    import(/* webpackChunkName: 'monaco_editor_lite' */ '~/editor/editor_lite')
-      .then(({ default: EditorLite }) => {
     const editorEl = document.getElementById('editor');
     const fileContentEl = document.getElementById('content');
     const form = document.querySelector('.js-ci-lint-form');
@@ -32,17 +28,5 @@ export default class CILintEditor {
     form.addEventListener('submit', () => {
       fileContentEl.value = this.editor.getValue();
     });
-      })
-      .catch(() => createFlash({ message: BLOB_EDITOR_ERROR }));
-  }
-
-  initAce() {
-    this.editor = window.ace.edit('ci-editor');
-    this.textarea = document.getElementById('content');
-
-    this.editor.getSession().setMode('ace/mode/yaml');
-    this.editor.on('input', () => {
-      this.textarea.value = this.editor.getSession().getValue();
-    });
   }
 }

app/views/projects/ci/lints/show.html.haml

 - page_title _("CI Lint")
 - page_description _("Validate your GitLab CI configuration file")
-- unless Feature.enabled?(:monaco_ci, default_enabled: true)
-  - content_for :page_specific_javascripts do
-    = page_specific_javascript_tag('lib/ace.js')
 
 %h2.pt-3.pb-3= _("Validate your GitLab CI configuration")
 
@@ -17,12 +14,9 @@
           .file-holder
             .js-file-title.file-title.clearfix
               = _("Contents of .gitlab-ci.yml")
-            - if Feature.enabled?(:monaco_ci, default_enabled: true)
             .file-editor.code
               .js-edit-mode-pane.qa-editor#editor{ data: { 'editor-loading': true } }<
                 %pre.editor-loading-content= params[:content]
-            - else
-              #ci-editor.ci-editor= @content
           = text_area_tag(:content, @content, class: 'hidden form-control span1', rows: 7, require: true)
         .col-sm-12
           .float-left.gl-mt-3

config/feature_flags/development/monaco_ci.yml

----
-name: monaco_ci
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/23666
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/249137
-group: group::editor
-type: development
-default_enabled: true

lib/gitlab/gon_helper.rb

@@ -44,7 +44,6 @@ module Gitlab
       # Initialize gon.features with any flags that should be
       # made globally available to the frontend
       push_frontend_feature_flag(:monaco_blobs, default_enabled: true)
-      push_frontend_feature_flag(:monaco_ci, default_enabled: true)
       push_frontend_feature_flag(:webperf_experiment, default_enabled: false)
       push_frontend_feature_flag(:snippets_binary_blob, default_enabled: false)
       push_frontend_feature_flag(:usage_data_api, default_enabled: false)

spec/features/projects/ci/lint_spec.rb

@@ -8,7 +8,21 @@ RSpec.describe 'CI Lint', :js do
   let(:project) { create(:project, :repository) }
   let(:user) { create(:user) }
 
-  shared_examples 'correct ci linting process' do
+  let(:content_selector) { '.content .view-lines' }
+
+  before do
+    stub_feature_flags(ci_lint_vue: false)
+    project.add_developer(user)
+    sign_in(user)
+
+    visit project_ci_lint_path(project)
+    editor_set_value(yaml_content)
+
+    wait_for('YAML content') do
+      find(content_selector).text.present?
+    end
+  end
+
   describe 'YAML parsing' do
     shared_examples 'validates the YAML' do
       before do
@@ -79,47 +93,4 @@ RSpec.describe 'CI Lint', :js do
       end
     end
   end
-  end
-
-  context 'with ACE editor' do
-    it_behaves_like 'correct ci linting process' do
-      let(:content_selector) { '.ace_content' }
-
-      before do
-        stub_feature_flags(monaco_ci: false)
-        stub_feature_flags(ci_lint_vue: false)
-        project.add_developer(user)
-        sign_in(user)
-
-        visit project_ci_lint_path(project)
-        find('#ci-editor')
-        execute_script("ace.edit('ci-editor').setValue(#{yaml_content.to_json});")
-
-        # Ace editor updates a hidden textarea and it happens asynchronously
-        wait_for('YAML content') do
-          find(content_selector).text.present?
-        end
-      end
-    end
-  end
-
-  context 'with Editor Lite' do
-    it_behaves_like 'correct ci linting process' do
-      let(:content_selector) { '.content .view-lines' }
-
-      before do
-        stub_feature_flags(monaco_ci: true)
-        stub_feature_flags(ci_lint_vue: false)
-        project.add_developer(user)
-        sign_in(user)
-
-        visit project_ci_lint_path(project)
-        editor_set_value(yaml_content)
-
-        wait_for('YAML content') do
-          find(content_selector).text.present?
-        end
-      end
-    end
-  end
 end