Add tests for getActiveNetwork.

Clean cherry-pick of ag/3918295
One-line adjustment for ag/3638326 which has not been put in AOSP.

Bug: 77737389
Test: runtest frameworks-net
Change-Id: I03ae2bbb08559f2cd44979e291c1f5d50eb215da
Merged-In: Iaa0285825735d3f16bba6e4946723a437fd9b0b9
Merged-In: Ia8f985b448251f911484e6bd63fa562bffc1b0e4
2 files changed