[ui] Remove integrations marketplace feature (#33097)

## Summary & Motivation

This PR removes the Integrations Marketplace feature from the Dagster UI. The change eliminates the marketplace navigation item, related UI components, and all supporting code for the feature.

## How I Tested These Changes

Verified that the UI loads correctly without the marketplace feature and no feature flag in User Settings, and confirmed that the navigation no longer shows the Integrations link.

## Changelog

[ui] Remove feature-flagged Integrations Marketplace, since individual code locations have docs available.

Author: hellendag

js_modules/dagster-ui/packages/ui-core/src/app/AppTopNav/AppTopNav.tsx

@@ -4,17 +4,15 @@ import {NavLink} from 'react-router-dom';
 import {AppTopNavRightOfLogo} from 'shared/app/AppTopNav/AppTopNavRightOfLogo.oss';
 import styled from 'styled-components';
 
-import {MarketplaceTopNavLink} from '../../integrations/MarketplaceTopNavLink';
-import {SearchTopNavItem} from '../../search/SearchTopNavItem';
-import {useFeatureFlags} from '../useFeatureFlags';
+import {useFullScreen} from './AppTopNavContext';
 import {GhostDaggyWithTooltip} from './GhostDaggy';
 import {
   reloadFnForWorkspace,
   useRepositoryLocationReload,
 } from '../../nav/useRepositoryLocationReload';
+import {SearchTopNavItem} from '../../search/SearchTopNavItem';
 import {LayoutContext} from '../LayoutProvider';
 import {ShortcutHandler} from '../ShortcutHandler';
-import {useFullScreen} from './AppTopNavContext';
 
 interface Props {
   children?: React.ReactNode;
@@ -30,7 +28,6 @@ export const AppTopNav = ({children, allowGlobalReload = false}: Props) => {
 };
 
 const AppTopNavImpl = ({children, allowGlobalReload = false}: Props) => {
-  const {flagMarketplace} = useFeatureFlags();
   const {reloading, tryReload} = useRepositoryLocationReload({
     scope: 'workspace',
     reloadFn: reloadFnForWorkspace,
@@ -57,7 +54,6 @@ const AppTopNavImpl = ({children, allowGlobalReload = false}: Props) => {
           </ShortcutHandler>
         ) : null}
         <SearchTopNavItem />
-        {flagMarketplace ? <MarketplaceTopNavLink /> : null}
         {children}
       </Box>
     </AppTopNavContainer>

js_modules/dagster-ui/packages/ui-core/src/app/ContentRoot.tsx

@@ -24,7 +24,6 @@ const SnapshotRoot = lazy(() => import('../snapshots/SnapshotRoot'));
 const GuessJobLocationRoot = lazy(() => import('../workspace/GuessJobLocationRoot'));
 const SettingsRoot = lazy(() => import('../settings/SettingsRoot'));
 const JobsRoot = lazy(() => import('../jobs/JobsRoot'));
-const IntegrationsRoot = lazy(() => import('../integrations/IntegrationsRoot'));
 
 export const ContentRoot = memo(() => {
   const {pathname} = useLocation();
@@ -92,9 +91,6 @@ export const ContentRoot = memo(() => {
           <Route path="/deployment">
             <SettingsRoot />
           </Route>
-          <Route path="/integrations">
-            <IntegrationsRoot />
-          </Route>
           <Route path="*" isNestingRoute>
             <FallthroughRoot />
           </Route>

js_modules/dagster-ui/packages/ui-core/src/app/FeatureFlags.oss.tsx

@@ -5,7 +5,6 @@ export enum FeatureFlag {
   flagDisableAutoLoadDefaults = 'flagDisableAutoLoadDefaults',
   flagAssetNodeFacets = 'flagAssetNodeFacets',
   flagUseNewObserveUIs = 'flagUseNewObserveUIs',
-  flagMarketplace = 'flagMarketplace',
   flagAssetGraphGroupsPerCodeLocation = 'flagAssetGraphGroupsPerCodeLocation',
   flagNavigationUpdate = 'flagNavigationUpdate',
   flagAssetCatalogSidebar = 'flagAssetCatalogSidebar',

js_modules/dagster-ui/packages/ui-core/src/app/navigation/mainNavigationItems.tsx

@@ -284,7 +284,7 @@ const SettingsItem = () => {
   );
 };
 
-export const getBottomGroups = ({featureFlags}: NavigationGroupConfig): NavigationGroup[] => {
+export const getBottomGroups = (_config: NavigationGroupConfig): NavigationGroup[] => {
   const searchGroup = [
     {
       key: 'search',
@@ -319,20 +319,5 @@ export const getBottomGroups = ({featureFlags}: NavigationGroupConfig): Navigati
     ],
   };
 
-  if (featureFlags.flagMarketplace) {
-    adminGroup.items.unshift({
-      key: 'marketplace',
-      label: 'Marketplace',
-      element: (
-        <NavItemWithLink
-          icon={<Icon name="compute_kind" />}
-          label="Integrations"
-          href="/integrations"
-          isActive={(_, currentLocation) => currentLocation.pathname.startsWith('/integrations')}
-        />
-      ),
-    });
-  }
-
   return [...searchGroup, adminGroup];
 };

js_modules/dagster-ui/packages/ui-core/src/app/useVisibleFeatureFlagRows.oss.tsx

@@ -15,10 +15,6 @@ export const useVisibleFeatureFlagRows = (): FeatureFlagRow[] => [
     key: 'Display faceted asset graph nodes',
     flagType: FeatureFlag.flagAssetNodeFacets,
   },
-  {
-    key: 'Display integrations marketplace',
-    flagType: FeatureFlag.flagMarketplace,
-  },
   {
     key: 'Disable WebSockets',
     flagType: FeatureFlag.flagDisableWebsockets,