remove unused filtered_search webpack bundle

app/assets/javascripts/filtered_search/filtered_search_bundle.js

-import './dropdown_emoji';
-import './dropdown_hint';
-import './dropdown_non_user';
-import './dropdown_user';
-import './dropdown_utils';
-import './filtered_search_dropdown_manager';
-import './filtered_search_dropdown';
-import './filtered_search_manager';
-import './filtered_search_tokenizer';
-import './filtered_search_visual_tokens';

config/webpack.config.js

@@ -46,7 +46,6 @@ function generateEntries() {
     balsamiq_viewer:      './blob/balsamiq_viewer.js',
     cycle_analytics:      './cycle_analytics/cycle_analytics_bundle.js',
     environments:         './environments/environments_bundle.js',
-    filtered_search:      './filtered_search/filtered_search_bundle.js',
     monitoring:           './monitoring/monitoring_bundle.js',
     mr_notes:             './mr_notes/index.js',
     notebook_viewer:      './blob/notebook_viewer.js',

spec/javascripts/test_bundle.js

@@ -126,7 +126,6 @@ if (process.env.BABEL_ENV === 'coverage') {
     './diff_notes/components/resolve_count.js',
     './dispatcher.js',
     './environments/environments_bundle.js',
-    './filtered_search/filtered_search_bundle.js',
     './graphs/graphs_bundle.js',
     './issuable/time_tracking/time_tracking_bundle.js',
     './main.js',