Local o365 plugin creating huge log files

[jwalits]

We have noticed our cron log files growing quite big, with a little under two thirds of the entries (~6.1 million lines) being this:

"Group ID 0005f82f-6b6e-4473-bb67-3b96527b9b11 in cache is up to date."

We managed to trace this down to the update_groups_cache function in the local/o365/classes/utils.php file. This file doesn't handle debugging correctly. It simply puts a mtrace which simply outputs to file regardless of whether debugging is enabled or not.

It would be better to convert to using the standard Moodle debugging function and only outputting if we are actively debugging.