Fix autofill FillEventHistoryTest on devices with physical keyboard.

The previous implementation expected the "press back" action to have
an effect of hiding the software keyboard, but it was not true for
devices that show no software keyboard by default (that is, laptops or
detachables with physical keyboard connected.) On such devices, the
back button terminated the current acitivity and made the test misbehaving.

To fix the situation, this CL inserts a simple after the press back event.

Bug: 109773582
Test: android.autofillservice.cts.FillEventHistoryTest
Change-Id: I437f30e0b8523322091d77adb644ea97c9ee8f84
1 file changed