Clean up predictive_back_swipe_edge_none_api

This CL removes all references to the swipe_edge_none_api flag. The
aconfig flag definition itself is not removed due to isExported=true.

Bug: 436710530
Bug: 362938401
Test: presubmit
Flag: EXEMPT flag cleanup
Change-Id: I56c7f8e854a6f1a3c80bc51df1aa844e966f654f