Default enableOnBackInvokedCallback to true with targetSdk>=36

Bug: 376407910
Test: presubmit
Test: Manual, i.e. verifying that app with targetSdk=36 has predictive back enabled by default
Flag: EXEMPT default value change
Change-Id: I1bfd92285a07e89e5f9b006deb69035d3213eb2e
1 file changed