chimera: Fix duplicate key supression

The postgresql driver for chimera has logic to avoid duplicate key
errors in postgresql while still throwing the SQLException on the
client side.

Unfortunately, the error code used is inconsistent with the error
code used in other logic that supresses the duplicate key error.

This patch resolves the problem: I checked the other places the
modified methods are called, and code that doesn't rely on the
isDuplicateKeyError just checks whther the error code starts with
'23'. This will still work after the change.

Target: trunk
Request: 2.9
Request: 2.8
Request: 2.7
Request: 2.6
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6999/