[Autofill CTS] Update logic of asserting accessibility title to reduce test flakiness

Previously UiBot is first getting the list of windows on screen then
check each window for the accessibility title. This method is somehow
flaky. This change updates to directly get AccessbilityWindowNodeInfo
from the UiObject, the ideal method mentioned in original TODO.

Verified by
- running testFillResponseAuthClientStateSetOnIntentOnly 10 times, test all pass:https://android-build.corp.google.com/builds/abtd/run/L60500030014782459
- running complete CtsAutofill test case, test all passes: https://android-build.corp.google.com/builds/abtd/run/L25200030014848040

Bug:b/430090355
Flag: TEST_ONLY
Test: CtsAutoFillServiceTestCase
Change-Id: I8fe4a4c112c4b16f28e0e7cda6251a4df8989ac5
1 file changed