Restore hard theshold for SLO of elastic_disk_space from 90% to 85%
Reverts increase in hard theshold for SLO of elastic_disk_space from 90% to 85%.
Incident issue: gitlab-com/gl-infra/production#8422 (closed)
Reverts increase in hard theshold for SLO of elastic_disk_space from 90% to 85%.
Incident issue: gitlab-com/gl-infra/production#8422 (closed)