disambiguate SQL server temp table constraint names

disambiguate SQL server temp table constraint names

This seems to be raising errors lately which was not the
case earlier, however SQL Server seems to produce name conflicts
for named constraints against temp tables in different databases.
I can raise the error every time here running two tests
from ComponentReflectionTest with -n2.  Unknown why the issue
is happening now and didn't occur for several months.

https://www.arbinada.com/en/node/1645 has some background.

Change-Id: I8854dfd88503fb855a7e12622ebe97c08915e5bb