ui: remove redundant flamegraph highlight Hide button

test/data/ui-screenshots/track_event_callstacks.test.ts/highlight-controls-can-be-kept-open-or-hidden/highlight-controls.png.sha256

@@ -1 +1 @@
-e0f9affc4210f4ce606e95808e701b712e6540372e7c1ae1dfa3ec2e6013db1c
+2de430b68660c23ee76028693a18c0fec5916271844a7a4a61270cfe1a100aa2

ui/src/test/track_event_callstacks.test.ts

@@ -167,8 +167,8 @@ test('highlight controls can be kept open or hidden', async () => {
     locator: drawerPanel,
   });
 
-  // Hiding the controls preserves the active highlight.
-  await highlightRow.locator('.pf-button', {hasText: 'Hide'}).click();
+  // Toggling the controls closed preserves the active highlight.
+  await highlightButton.click();
   await expect(highlightRow).toHaveCount(0);
   await expect(highlightButton).toHaveClass(/pf-active/);
 });

ui/src/widgets/tree_explorer_filter_bar.ts

@@ -257,13 +257,6 @@ export class TreeExplorerFilterBar implements m.ClassComponent<TreeExplorerFilte
               title: 'Clear highlight',
               onclick: () => attrs.onHighlightChange(''),
             }),
-          m(Button, {
-            label: 'Hide',
-            compact: true,
-            onclick: () => {
-              this.showHighlightSearch = false;
-            },
-          }),
         ),
     );
   }