New FIELD_AUTOFILL_COMPAT_MODE field.

This field is used on pretty much all Autofill metrics, except
AUTOFILL_USERDATA_UPDATED, AUTOFILL_SERVICE_DISABLED_SELF, and
AUTOFILL_INVALID_PERMISSION.

Test: atest CtsAutoFillServiceTestCases
Test: adb shell logcat -b events | grep sysui

Bug: 79351659

Change-Id: I2e2f3dcc780a3896162b158926f5ee89c7cb342d