openshift_prometheus: remove block duration settings

The prometheus block duration settings should not be changed from their defaults.
See also: https://github.com/prometheus/prometheus/pull/3618

roles/openshift_prometheus/README.md

@@ -31,7 +31,7 @@ For default values, see [`defaults/main.yaml`](defaults/main.yaml).
 
 e.g
 ```
-openshift_prometheus_args=['--storage.tsdb.retention=6h', '--storage.tsdb.min-block-duration=5s', '--storage.tsdb.max-block-duration=6m']
+openshift_prometheus_args=['--storage.tsdb.retention=6h', '--query.timeout=2m']
 ```
 
 ## PVC related variables

roles/openshift_prometheus/defaults/main.yaml

@@ -14,7 +14,7 @@ openshift_prometheus_node_selector: {"region":"infra"}
 openshift_prometheus_additional_rules_file: null
 
 #prometheus application arguments
-openshift_prometheus_args: ['--storage.tsdb.retention=6h', '--storage.tsdb.min-block-duration=2m']
+openshift_prometheus_args: ['--storage.tsdb.retention=6h']
 
 # storage
 # One of ['emptydir', 'pvc']