Revert "Add missing flush() calls to passwords_section_test"

This reverts commit e7be6d6b.

Reason for revert: Being reverted as part of a chain of CLs suspected of causing problems - see https://chromium-review.googlesource.com/c/chromium/src/+/2252612

Original change's description:
> Add missing flush() calls to passwords_section_test
> 
> crrev.com/c/2246157 is suspect of causing failures in
> CrSettingsPasswordsSectionV3Test. This could be caused by click events
> in the new tests not being flushed, so this CL adds missing flush()
> calls.
> 
> Bug: None
> Change-Id: I3abff7ddb894aa4a3cb3f7cf0dd2a06c7f05ec73
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2252138
> Commit-Queue: Victor Vianna <victorvianna@google.com>
> Reviewed-by: Friedrich [CET] <fhorschig@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#779837}

TBR=treib@chromium.org,fhorschig@chromium.org,victorvianna@google.com

Change-Id: Id52fe41ab407b18dd154470832ba6d7798239653
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: None
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2252613Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#779916}

chrome/test/data/webui/settings/passwords_section_test.js

@@ -1358,12 +1358,10 @@ suite('PasswordsSection', function() {
       // Uncheck the account checkboxes then confirm. Only the device copy is
       // removed.
       removeDialog.$.removeFromAccountCheckbox.click();
-      flush();
       assertTrue(
           !removeDialog.$.removeFromAccountCheckbox.checked &&
           removeDialog.$.removeFromDeviceCheckbox.checked);
       removeDialog.$.removeButton.click();
-      flush();
       const removedIds =
           await passwordManager.whenCalled('removeSavedPasswords');
       assertTrue(removedIds.includes(deviceCopy.id));