[SR] Change VBucket::abort failures to 'err' level
[SR] Change VBucket::abort failures to 'err' level

Change the level of the VBucket::abort() log messages for failing to
find a prepared SyncWrite to 'error' status.

Change-Id: I6a9c158445581de44622a8a07f915aa57f7ccda6
Reviewed-on: http://review.couchbase.org/110868
Reviewed-by: Ben Huddleston <6c0d3f0e87b08a8c49786ca528f2c4b1ad3d36f3@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine