topic_list: Fix and improve selectors related to the topic list filter.

web/src/hotkey.js

@@ -453,7 +453,7 @@ export function process_escape_key(e) {
 
         // When the input is focused, we blur and clear the input. A second "Esc"
         // will zoom out, handled below.
-        if (stream_list.is_zoomed_in() && $("#left-sidebar-filter-topic-input").is(":focus")) {
+        if (stream_list.is_zoomed_in() && $("#topic_filter_query").is(":focus")) {
             topic_list.clear_topic_search(e);
             return true;
         }

web/src/stream_list.ts

@@ -425,7 +425,7 @@ export function zoom_in_topics(options: {stream_id: number | undefined}): void {
             $elt.show();
             // Add search box for topics list.
             $elt.children("div.bottom_left_row").append($(render_filter_topics()));
-            $("#left-sidebar-filter-topic-input").trigger("focus");
+            $("#topic_filter_query").trigger("focus");
             topic_list.setup_topic_search_typeahead();
         } else {
             $elt.hide();

web/src/topic_list.ts

@@ -494,7 +494,7 @@ export function zoom_in(): void {
 }
 
 export function get_left_sidebar_topic_search_term(): string {
-    return $("#left-sidebar-filter-topic-input .input").text().trim();
+    return $("#topic_filter_query").text().trim();
 }
 
 export function get_typeahead_search_term(): string {