Uses autofill callback to throttle performance tests.

Currently the Autofill performance tests work fine, but if we change IAutofillManager
to make oneway binder calls, the tests will crash because of the excessive number of
unfinished binder transactions.

We can fix this issue by using the autofill callbacks that are shown when the UI is shown
or hidden.

Test: mmma -j ./frameworks/base/apct-tests/perftests/autofill/ && \
  adb install -r $OUT/data/app/AutofillPerfTests/AutofillPerfTests.apk && \
  adb shell am instrument -w -e class android.view.autofill.LoginTest \
  com.android.perftests.autofill/android.support.test.runner.AndroidJUnitRunner

Bug: 73536867

Change-Id: I216e67ca97cab059851b0873601e82b368a6abea