Remove the `release_search_filter` feature flag

This commit removes the `release_search_filter` feature flag.
This flag was already enabled by default, so this change makes no
noticeable change to the product.

app/assets/javascripts/filtered_search/issuable_filtered_search_token_keys.js

 import FilteredSearchTokenKeys from './filtered_search_token_keys';
 import { __ } from '~/locale';
 
-export const tokenKeys = [];
-
-tokenKeys.push(
+export const tokenKeys = [
   {
     key: 'author',
     type: 'string',
@@ -28,27 +26,23 @@ tokenKeys.push(
     icon: 'clock',
     tag: '%milestone',
   },
-);
-
-if (gon && gon.features && gon.features.releaseSearchFilter) {
-  tokenKeys.push({
+  {
     key: 'release',
     type: 'string',
     param: 'tag',
     symbol: '',
     icon: 'rocket',
     tag: __('tag name'),
-  });
-}
-
-tokenKeys.push({
+  },
+  {
     key: 'label',
     type: 'array',
     param: 'name[]',
     symbol: '~',
     icon: 'labels',
     tag: '~label',
-});
+  },
+];
 
 if (gon.current_user_id) {
   // Appending tokenkeys only logged-in

app/controllers/projects/issues_controller.rb

@@ -44,7 +44,6 @@ class Projects::IssuesController < Projects::ApplicationController
 
   before_action do
     push_frontend_feature_flag(:vue_issuable_sidebar, project.group)
-    push_frontend_feature_flag(:release_search_filter, project, default_enabled: true)
   end
 
   respond_to :html

app/controllers/projects/merge_requests_controller.rb

@@ -25,7 +25,6 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
 
   before_action do
     push_frontend_feature_flag(:vue_issuable_sidebar, @project.group)
-    push_frontend_feature_flag(:release_search_filter, @project, default_enabled: true)
     push_frontend_feature_flag(:async_mr_widget, @project)
   end
 

ee/spec/javascripts/filtered_search/issues_filtered_search_token_keys_spec.js

@@ -58,7 +58,7 @@ describe('Issues Filtered Search Token Keys (EE)', () => {
   describe('searchBySymbol', () => {
     it('should return weight tokenKey when found by weight symbol', () => {
       const tokenKeys = IssuableFilteredSearchTokenKeys.get();
-      const match = tokenKeys.find(tk => tk.key === weightTokenKey.key);
+      const match = tokenKeys.find(tk => tk.symbol === weightTokenKey.symbol);
       const result = IssuableFilteredSearchTokenKeys.searchBySymbol(weightTokenKey.symbol);
 
       expect(result).toEqual(match);