Fix data error handling.

In change I5776324a I made DataConnection.reset asynchronous.
That was a mistake as callers to cleanUpConnection assumed
it was synchronous. Added DataConnection.resetSynchronously
as a fix, someday the trackers will become asynchronous and
this won't be necessary.

Change-Id: I4669901e5c47a712212bb388c35fbb9f9ff603a7