Add DBDuplicateEntry detection for mysqlconnector driver

Actually, adjust the mysql regex to match on the "Duplicate entry 'foo'
for key 'bar'" error string that is presumably buried deep within mysqld
itself, with less regard to specific punctuation.
Hopefully this will be portable between all mysql drivers.

Change-Id: I241c5cb61a6335857942bf79ee2301ae0c94ff6e
Merge "Add DBDuplicateEntry detection for mysqlconnector driver"