don't check standard_conforming_strings less than server version 8.2

don't check standard_conforming_strings less than server version 8.2

Fixed a small regression where the query for "show
standard_conforming_strings" upon initialization would be emitted even if
the server version info were detected as less than version 8.2, previously
it would only occur for server version 8.2 or greater. The query fails on
Amazon Redshift which reports a PG server version older than this value.

Fixes: #5698
Change-Id: Ib27ce4b05106d986a618597e4cf253504f981bf1