Remove readonly rootfs Elasticsearch

This removes ReadonlyRootfs from
Elasticsearch data pods as this is
required in order for the data pods
to recover from outages

Change-Id: I603d3a25b6580eab20e2b20e1b1cd0cf740c7ab2

elasticsearch/values.yaml

@@ -196,7 +196,10 @@ pod:
             add:
               - IPC_LOCK
               - SYS_RESOURCE
-          readOnlyRootFilesystem: true
+          # NOTE: This was changed from true to false to account for
+          # recovery scenarios when the data pods are unexpectedly lost due to
+          # node outages and shard/index recovery is required
+          readOnlyRootFilesystem: false
   affinity:
       anti:
         type: