Fixed FillCallback.onFailure() and SaveCallback.onFailure() behavior.

FillCallback.onFailure() was not working as intented - it finished the session
on AutofillManagerService, but didn't update the client state on
AutofillManager.

And both of these methods were displaying Toasts to the user, which is something
the autofill services could take care of. Hence, for services target with SDK
Q, the message is ignored.

Also added a new Autofill Metric: FIELD_AUTOFILL_MESSAGE_LEN

Test: atest CtsAutoFillServiceTestCases:android.autofillservice.cts.LoginActivityTest#testAutofillAgainAfterOnFailure
Test: atest CtsAutoFillServiceTestCases # to make sure it didn't break anything
Test: time mmm -j frameworks/base/:doc-comment-check-docs
Test: m -j update-api

Bug: 112192360
Fixes: 116103297

Change-Id: I499909200980943dedf1fc8524dd1f14b49e2158