spacemanager: Another hsqldb schema management fix

HSQLDB track trigger dependencies, so we have to drop triggers before
we can rename columns.

HSQLDB 2.3.2 also seems to have a bug in which it creates dependencies from
triggers that do not even refer to the column in question.  The patch
downgrades to 2.3.1.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6832/