Delete atoms.proto from statsd

Use the atoms.proto in proto_logging as the source of truth. Also
migrates statsd log api gen to use the new atoms.proto

Bug: 167962588
Test: m -j && m CtsStatsdAtomHostTestCases

Change-Id: I36ec354d273dceace5245d7634c68ac63dc5a8cd
Merged-In: I36ec354d273dceace5245d7634c68ac63dc5a8cd