Revert onNetworkActive callback behavior on U+

aosp/2605757 changed onNetworkActive callback behavior on U+ but this
change was not merged to U release branch.
This CL reverts the behavior change and keep the current behavior on U+.

Bug: 279380356
Bug: 291870075
Test: atest FrameworksNetTests
Change-Id: I91ccc7ee93f0827986401f316997b4a2df11318f