Switch to positive naming for NetworkMonitor's Networks.

"mNonPrivateDnsBypassNetwork" is not very easy to understand.

Bug: 122652057
Test: atest FrameworksNetTests NetworkStackTests
Change-Id: If5801c81c6ef222b46f631bd6570dcd0fea465bd
Merged-In: If5801c81c6ef222b46f631bd6570dcd0fea465bd
(cherry picked from commit 669dc6ce)