Improved Application.getAutofillClient()

- Fixed usage of activity instead of record.activity
- Added (optional) verbose logging

Bug: 74793485
Test: atest CtsAutoFillServiceTestCases:VirtualContainerActivityTest#testAutofill_appContext\
CtsAutoFillServiceTestCases:VirtualContainerActivityCompatModeTest#testAutofill_appContext

Change-Id: I03721cab6428e580b13444bf045f33dc3d787a8d