Bug 1950199: Reset mahara timezone after saml cron breaks it

There is a part of the SAML core code that sets the timezone to UTC
when creating the metadata refresh file.

This causes all cron jobs after it in the same run to use the
incorrect timezone

Change-Id: Id6c741b439ef42c50edc844878969f90e24a29b6
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit 5a239852)