Remove backward compatibility flag am: d1bedc4e64 am: 0d8879b0f2 am: 774cf9e68c am: 5b968178e0

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1413548

Change-Id: I0f5eb677b9b3f5b1905ade00c2e6f1eb89b743e5