[Autofill Framework] Change fill_fields_from_current_session_only from
aconfig flag to device config flag

Registered a test run on CtsAutoFillServiceTestCases for this topic: https://android-build.corp.google.com/abtd/run/L34600030002636795/. Tests all passed except three known failures.

Bug: b/315911323
Test: atest CtsAutoFillServiceTestCases
Change-Id: Ia3a8bd68c19a952db4caa593a928d82a66cd32e2
2 files changed