Fix typo in MySQL upgrade tasks.
Fix typo in MySQL upgrade tasks.

The upgrade tasks are failing because podman can't locate
the log output file during the MySQL upgrade step. The
parameter LOG_DIR was misswritten into LOGDIR and Heat
could not subsitute it.

Change-Id: I19a7b8495a4510bff59feff43a6042da0e74eb5a
Closes-Bug: #1853162

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates