Remove searchable envs dropdown feature flag

Environments dropdown in the monitoring dashboard will
have a search input to search for environments

app/assets/javascripts/monitoring/components/dashboard.vue

@@ -239,9 +239,6 @@ export default {
         this.externalDashboardUrl.length
       );
     },
-    shouldRenderSearchableEnvironmentsDropdown() {
-      return this.glFeatures.searchableEnvironmentsDropdown;
-    },
     shouldShowEnvironmentsDropdownNoMatchedMsg() {
       return !this.environmentsLoading && this.filteredEnvironments.length === 0;
     },
@@ -407,7 +404,6 @@ export default {
               }}</gl-dropdown-header>
               <gl-dropdown-divider />
               <gl-search-box-by-type
-                v-if="shouldRenderSearchableEnvironmentsDropdown"
                 ref="monitorEnvironmentsDropdownSearch"
                 class="m-2"
                 @input="debouncedEnvironmentsSearch"
@@ -428,7 +424,6 @@ export default {
                 >
               </div>
               <div
-                v-if="shouldRenderSearchableEnvironmentsDropdown"
                 v-show="shouldShowEnvironmentsDropdownNoMatchedMsg"
                 ref="monitorEnvironmentsDropdownMsg"
                 class="text-secondary no-matches-message"

app/assets/javascripts/monitoring/stores/getters.js

@@ -62,8 +62,6 @@ export const metricsWithData = state => groupKey => {
  * Filter environments by names.
  *
  * This is used in the environments dropdown with searchable input.
- * Also, this searchable dropdown is behind `searchable_environments_dropdown`
- * feature flag
  *
  * @param {Object} state
  * @returns {Array} List of environments

app/controllers/projects/environments_controller.rb

@@ -14,7 +14,6 @@ class Projects::EnvironmentsController < Projects::ApplicationController
   before_action :expire_etag_cache, only: [:index], unless: -> { request.format.json? }
   before_action only: [:metrics, :additional_metrics, :metrics_dashboard] do
     push_frontend_feature_flag(:prometheus_computed_alerts)
-    push_frontend_feature_flag(:searchable_environments_dropdown)
   end
   before_action do
     push_frontend_feature_flag(:auto_stop_environments)

changelogs/unreleased/34021-environments-dropdown-remove-feature-flag.yml

+---
+title: Enable search and filter in environments dropdown in monitoring dashboard
+merge_request: 23942
+author:
+type: added

spec/frontend/monitoring/components/dashboard_spec.js

@@ -255,9 +255,6 @@ describe('Dashboard', () => {
         {
           attachToDocument: true,
           stubs: ['graph-group', 'panel-type'],
-          provide: {
-            glFeatures: { searchableEnvironmentsDropdown: true },
-          },
         },
       );