Remove ConnectivityManager swapActiveStatsMap API

swapActiveStatsMap is temporary added for the NetworkStatsFactory to
call BpfNetMaps#swapActiveStatsMap in tethering mainline module. Now
NetworkStatsFactory already be mainlined, calling BpfNetMaps#swapActiveStatsMap
directly.

Bug: 218494448
Test: atest ConnectivityCoverageTests
      atest FrameworksNetTests
Change-Id: I3358e4ac5fb7ed0964273afdbccd1b4128ca7645
7 files changed