Call get_pgsql_connection_info from _test_postgresql_opportunistically

The _test_postgresql_opportunistically method was calling the method to
parse the mysql connection URL which is wrong when there is one
specifically for postgresql, so call the right method.

This wasn't causing issues obviously but is something that needs to be
cleaned up regardless.

Closes-Bug: #1274718

Change-Id: Ic572e612c7ce31d854dc7258aa9c8b89a197260e
Merge "Call get_pgsql_connection_info from _test_postgresql_opportunistically"