remove Write-Only on RuntimeScriptAction[parameters] (Azure#21427)

Co-authored-by: v-yuchenli <v-yuchenli@microsoft.com>

Author: 2 people

specification/hdinsight/resource-manager/Microsoft.HDInsight/stable/2021-06-01/cluster.json

@@ -1656,11 +1656,7 @@
         },
         "parameters": {
           "type": "string",
-          "description": "The parameters for the script",
-          "x-ms-mutability": [
-            "create",
-            "update"
-          ]
+          "description": "The parameters for the script"
         },
         "roles": {
           "type": "array",