reduce size of master nodes in the production logging ES cluster
refs: https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/10094
The masters were resized from 4GB to 16GB as part of the issue linked above. Their current CPU utilization is around 15%. The problem we were facing was related to saturation on masters so this should be very carefully examined before any decision is made.
Similarly to https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/10229 let's:
- wait for 7.7 upgrade
- continue efforts to reduce number of fields and number of shards
- collect monitoring data that will further suggest that it's safe to resize the masters