[TEST] Fixed get_source/60_realtime_refresh REST test to work against multiple nodes

Replaced also wait for yellow with wait for green when using no replicas.

get_source/60_realtime_refresh tests per shard refresh using refresh:true and realtime:true in get api. We might run into troubles though if we have a replica that gets initialized after a doc was indexed without a refresh, as that doc will be found when searching against that specific replica shard (as a refresh happens automatically before a replica gets exposed as started).

rest-api-spec/test/exists/60_realtime_refresh.yaml

@@ -9,9 +9,10 @@
            index:
              refresh_interval: -1
              number_of_replicas: 0
+
  - do:
       cluster.health:
-          wait_for_status: yellow
+          wait_for_status: green
 
  - do:
       index:

rest-api-spec/test/get/60_realtime_refresh.yaml

@@ -12,7 +12,7 @@
 
  - do:
       cluster.health:
-          wait_for_status: yellow
+          wait_for_status: green
 
  - do:
       index:

rest-api-spec/test/get_source/60_realtime_refresh.yaml

@@ -8,10 +8,11 @@
           body:
               settings:
                   refresh_interval: -1
+                  number_of_replicas: 0
 
  - do:
       cluster.health:
-          wait_for_status: yellow
+          wait_for_status: green
 
  - do:
       index:

rest-api-spec/test/mget/60_realtime_refresh.yaml

@@ -12,7 +12,7 @@
 
  - do:
       cluster.health:
-          wait_for_status: yellow
+          wait_for_status: green
 
  - do:
       index: