Remove save_issuable_health_status feature flag in frontend

Remove the flag since it has been defaulted to on in production
for some time without issues

app/assets/javascripts/sidebar/queries/sidebarDetailsForHealthStatusFeatureFlag.query.graphql

-query($fullPath: ID!, $iid: String!) {
-  project(fullPath: $fullPath) {
-    issue(iid: $iid) {
-      iid
-    }
-  }
-}

app/assets/javascripts/sidebar/services/sidebar_service.js

 import sidebarDetailsQuery from 'ee_else_ce/sidebar/queries/sidebarDetails.query.graphql';
-import sidebarDetailsForHealthStatusFeatureFlagQuery from 'ee_else_ce/sidebar/queries/sidebarDetailsForHealthStatusFeatureFlag.query.graphql';
 import axios from '~/lib/utils/axios_utils';
 import createGqClient, { fetchPolicies } from '~/lib/graphql';
 
@@ -27,14 +26,10 @@ export default class SidebarService {
   }
 
   get() {
-    const hasHealthStatusFeatureFlag = gon.features && gon.features.saveIssuableHealthStatus;
-
     return Promise.all([
       axios.get(this.endpoint),
       gqClient.query({
-        query: hasHealthStatusFeatureFlag
-          ? sidebarDetailsForHealthStatusFeatureFlagQuery
-          : sidebarDetailsQuery,
+        query: sidebarDetailsQuery,
         variables: {
           fullPath: this.fullPath,
           iid: this.iid.toString(),

ee/app/assets/javascripts/sidebar/queries/sidebarDetails.query.graphql

 query($fullPath: ID!, $iid: String!) {
   project(fullPath: $fullPath) {
     issue(iid: $iid) {
-      iid
+      healthStatus
     }
   }
 }

ee/app/assets/javascripts/sidebar/queries/sidebarDetailsForHealthStatusFeatureFlag.query.graphql

-query($fullPath: ID!, $iid: String!) {
-  project(fullPath: $fullPath) {
-    issue(iid: $iid) {
-      healthStatus
-    }
-  }
-}

ee/app/controllers/ee/projects/issues_controller.rb

@@ -10,10 +10,6 @@ module EE
         include DescriptionDiffActions
 
         before_action :whitelist_query_limiting_ee, only: [:update]
-
-        before_action do
-          push_frontend_feature_flag(:save_issuable_health_status, project.group, default_enabled: true)
-        end
       end
 
       private

ee/spec/features/issues/issue_sidebar_spec.rb

@@ -125,21 +125,6 @@ RSpec.describe 'Issue Sidebar' do
         expect(page).not_to have_selector('.block.health-status')
       end
     end
-
-    it 'pushes frontend feature flag saveIssuableHealthStatus' do
-      visit_issue(project, issue)
-
-      expect(page).to have_pushed_frontend_feature_flags(saveIssuableHealthStatus: true)
-    end
-
-    context 'when save_issuable_health_status feature flag is disabled' do
-      it 'pushes disabled frontend feature flag saveIssuableHealthStatus' do
-        stub_feature_flags(save_issuable_health_status: false)
-        visit_issue(project, issue)
-
-        expect(page).to have_pushed_frontend_feature_flags(saveIssuableHealthStatus: false)
-      end
-    end
   end
 
   context 'Iterations', :js do