Deflake drawer e2e test

Bug:none
Change-Id: I32e0f6207fe8418554345df9eecb30eee44b4d6f
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7748710
Reviewed-by: Piotr Paulski <piotrpaulski@chromium.org>
Auto-Submit: Kateryna Prokopenko <kprokopenko@chromium.org>
Commit-Queue: Piotr Paulski <piotrpaulski@chromium.org>

Author: Kateryna Prokopenko

test/e2e/inspector/drawer.test.ts

@@ -179,12 +179,14 @@ describe('Drawer', () => {
     // 1) Show the drawer and measure initial metrics
     await devToolsPage.pressKey('Escape');
     await devToolsPage.waitFor(DRAWER_SELECTOR);
+    await devToolsPage.renderCoordinatorQueueEmpty();
     const opened = await getHeaderMetrics();
     assert.exists(opened);
 
     // 2) Close the drawer and verify metrics
     await devToolsPage.click(CLOSE_BUTTON_SELECTOR);
     await devToolsPage.waitForNone(DRAWER_SELECTOR);
+    await devToolsPage.renderCoordinatorQueueEmpty();
     const closed = await getHeaderMetrics();
     assert.exists(closed);
 
@@ -194,6 +196,7 @@ describe('Drawer', () => {
     // 3) Re-open the drawer and verify metrics
     await devToolsPage.pressKey('Escape');
     await devToolsPage.waitFor(DRAWER_SELECTOR);
+    await devToolsPage.renderCoordinatorQueueEmpty();
     const reopened = await getHeaderMetrics();
     assert.exists(reopened);