Fixed search param being used in the add issues modal

Also fixed the input placeholder in the modal not being displayed when first opened

app/assets/javascripts/boards/components/modal/filters.js

@@ -14,6 +14,8 @@ export default {
 
     this.filteredSearch = new FilteredSearchBoards(this.store);
     this.filteredSearch.removeTokens();
+    this.filteredSearch.handleInputPlaceholder();
+    this.filteredSearch.toggleClearSearchButton();
   },
   beforeDestroy() {
     this.filteredSearch.cleanup();

app/assets/javascripts/boards/filtered_search_boards.js

@@ -28,6 +28,8 @@ export default class FilteredSearchBoards extends gl.FilteredSearchManager {
     [].forEach.call(tokens, (el) => {
       el.parentNode.removeChild(el);
     });
+
+    this.filteredSearchInput.value = '';
   }
 
   updateTokens() {