pgsql: Run the "tablespace" regression test first not last.

Log Message:
-----------
Run the "tablespace" regression test first not last.  The former placement
renders useless one of the few test methodologies we have for WAL replay,
which is to intentionally crash the system just after completing the
regression tests and see if it recovers to the expected database state.
The reason is that DROP TABLESPACE forces a checkpoint, so there's essentially
no WAL available for replay after the tests complete.

Modified Files:
--------------
    pgsql/src/test/regress:
        parallel_schedule (r1.56 -> r1.57)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/parallel_schedule?r1=1.56&r2=1.57)
        serial_schedule (r1.53 -> r1.54)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/serial_schedule?r1=1.53&r2=1.54)