Fix DB2 and nosql ceilometer dbsync

* Remove very old and now incorrect check for running
ceilometer-dbsync with nosql.  This is fine to do now, and is
needed when nosql is used for DB2 with ceilometer.

Change-Id: Id31d7dffb3e01513bb0470a7a6f5f07118dc28ef
Closes-Bug: #1373600