On GitLab.com, we see that cron jobs sometimes don't run. This appears to be
because the process that polls for current cron jobs only has a 60 second
validity period, so if (for whatever reason) it misses those 60 seconds, we have
to wait until the next execution.

For the usage ping, this is particularly problematic, as that's only scheduled
to run once a week.

Changing it to run for every minute in a 10 minute period should work around
this, if the above diagnosis is correct. The job itself obtains an exclusive
lease for 24 hours, so rescheduling in quick succession is safe.