Switch CI bucket to intelligent tiering

Switch CI bucket to intelligent tiering

We currently upload approximately 166 GB/day into this bucket (estimate based on
duration of storage and total current size). My estimate is that this change
should decrease our costs (which are currently in credits) and is in the worst
case (if all objects are brought into hot storage due to unanticipated frequent
access) only going to add an additional ~$4 to the monthly bill. If access is
rare (as expected) to most objects then we expect to save approximately
~$350/month (after this change takes full effect in ~168 days).