REPEATABLE

Problem:
--------
Two MTR tests in the main suite - ctype_gb18030_binlog and ctype_ldml fail
when run with a --repeat value greater than one due to improper cleanup in
them.

Fix:
----
Performing cleanup in both tests by removing a couple of created files so
that they don't affect their repetitions. Also, --force-restart has been
added to the opt file for main.ctype_ldml so that the error log is created
afresh for repeated runs.

This patch is based on a contribution from Daniel Black.

Reviewed by:
Bernt Johnsen <bernt.johnsen@oracle.com>
RB #12351