Re-add callback to onCancel() when screen is touched outside Save UI.

That callback was accidentally removed because it should not trigger the
negative listener, but the right approach was to pass a null listener.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases

Bug: 66235266
Fixes: 66944844

Change-Id: I5b71d3d03335d952e3b47078d1373f9783366437