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: com.android.window.flags.predictive_back_default_enable_sdk_36
Change-Id: I04ced985c84c9e1d2a9c3a37b9d5addf4d5357da
2 files changed