Raise ES disk space alert thresholds

the real cluster watermarks are the following:
  "cluster.routing.allocation.disk.watermark.high": "90%"
  "cluster.routing.allocation.disk.watermark.low": "85%"

set the alerts' thresholds to 85% and 80% (5% behind the real watermark)

Related-PROD: PROD-33841

Change-Id: I95ab8752fd60f8d698ee04386e296d42892b376f
2 files changed