pgsql: Remove forced CHECKPOINT in regression tests --- redundant now

Log Message:
-----------
Remove forced CHECKPOINT in regression tests --- redundant now that
CREATE DATABASE does one internally.

Modified Files:
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pgsql/src/test/regress:
pg_regress.sh (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.sh.diff?r1=1.57&r2=1.58)