Remove hidden deprecated getActiveNetworkQuotaInfo

getActiveNetworkQuotaInfo has never been in API surface since it
was introduced. It became essentially functionless since android O,
so there should be no usage dependency upon the hidden method,
In order to support ConnectivityService mainline, remove the
useless function to prevent necessary dependency.

Bug: 172183305
Test: atest FrameworksNetTests
Change-Id: Ia685b3260256d465ef614b2f577d13344074c787