Revert "Remove the stats protos from ConnectivityService until tests are added"

This reverts commit ec8c31d3f5908b465289e61a8b3a414e34a8c740.

Reason for revert: Test coverage excludes ConnectivityService metrics and classes via cl/489997332

Change-Id: Ia96f030af983cc2b42ddd82371679d1ccaadd743
1 file changed