Clean up issue_boards_filtered_search feature flag

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app/assets/javascripts/boards/filtered_search_boards.js

-import { transformBoardConfig } from 'ee_else_ce/boards/boards_util';
-import FilteredSearchManager from 'ee_else_ce/filtered_search/filtered_search_manager';
-import IssuableFilteredSearchTokenKeys from 'ee_else_ce/filtered_search/issuable_filtered_search_token_keys';
-import { updateHistory } from '~/lib/utils/url_utility';
-import FilteredSearchContainer from '../filtered_search/container';
-import vuexstore from './stores';
-
-export default class FilteredSearchBoards extends FilteredSearchManager {
-  constructor(store, updateUrl = false, cantEdit = []) {
-    super({
-      page: 'boards',
-      isGroupDecendent: true,
-      stateFiltersSelector: '.issues-state-filters',
-      isGroup: IS_EE,
-      useDefaultState: false,
-      filteredSearchTokenKeys: IssuableFilteredSearchTokenKeys,
-    });
-
-    this.store = store;
-    this.updateUrl = updateUrl;
-
-    // Issue boards is slightly different, we handle all the requests async
-    // instead or reloading the page, we just re-fire the list ajax requests
-    this.isHandledAsync = true;
-    this.cantEdit = cantEdit.filter((i) => typeof i === 'string');
-    this.cantEditWithValue = cantEdit.filter((i) => typeof i === 'object');
-
-    if (vuexstore.state.boardConfig) {
-      const boardConfigPath = transformBoardConfig(vuexstore.state.boardConfig);
-      // TODO Refactor: https://gitlab.com/gitlab-org/gitlab/-/issues/329274
-      // here we are using "window.location.search" as a temporary store
-      // only to unpack the params and do another validation inside
-      // 'performSearch' and 'setFilter' vuex actions.
-      if (boardConfigPath !== '') {
-        const filterPath = window.location.search ? `${window.location.search}&` : '?';
-        updateHistory({
-          url: `${filterPath}${transformBoardConfig(vuexstore.state.boardConfig)}`,
-        });
-      }
-    }
-  }
-
-  updateObject(path) {
-    const groupByParam = new URLSearchParams(window.location.search).get('group_by');
-    this.store.path = `${path.substr(1)}${groupByParam ? `&group_by=${groupByParam}` : ''}`;
-
-    updateHistory({
-      url: `?${path.substr(1)}${groupByParam ? `&group_by=${groupByParam}` : ''}`,
-    });
-    vuexstore.dispatch('performSearch');
-  }
-
-  removeTokens() {
-    const tokens = FilteredSearchContainer.container.querySelectorAll('.js-visual-token');
-
-    // Remove all the tokens as they will be replaced by the search manager
-    [].forEach.call(tokens, (el) => {
-      el.parentNode.removeChild(el);
-    });
-
-    this.filteredSearchInput.value = '';
-  }
-
-  updateTokens() {
-    this.removeTokens();
-
-    this.loadSearchParamsFromURL();
-
-    // Get the placeholder back if search is empty
-    this.filteredSearchInput.dispatchEvent(new Event('input'));
-  }
-
-  canEdit(tokenName, tokenValue) {
-    if (this.cantEdit.includes(tokenName)) return false;
-    return (
-      this.cantEditWithValue.findIndex(
-        (token) => token.name === tokenName && token.value === tokenValue,
-      ) === -1
-    );
-  }
-}