Uses Theme.DeviceDefault.Light.Panel for non-TV autofill themes.

(TV themes will be fixed in a separate CL)

Test: manual verification using sample service and Google Autofill
Test: atest CtsAutoFillServiceTestCases # to make sure it didn't break anything

Bug: 116457731
Fixes: 115574534

Change-Id: I1b1ca7ddc5101dc7a188156fa82ede0b41700297