fix: updated the DA catalog config to use the "Default" resource group and default to "null" in varaibles.tf (#704)

Author: piyush117

ibm_catalog.json

@@ -56,7 +56,17 @@
             },
             {
               "key": "existing_resource_group_name",
-              "required": true
+              "display_name": "resource_group",
+              "default_value": "Default",
+              "description": "The name of an existing resource group to provision the resources.",
+              "custom_config": {
+                "type": "resource_group",
+                "grouping": "deployment",
+                "original_grouping": "deployment",
+                "config_constraints": {
+                  "identifier": "rg_name"
+                }
+              }
             },
             {
               "key": "prefix",

solutions/fully-configurable/variables.tf

@@ -7,6 +7,7 @@ variable "ibmcloud_api_key" {
 variable "existing_resource_group_name" {
   type        = string
   description = "The name of an existing resource group to provision the resources. If not provided the default resource group will be used."
+  default     = null
 }
 
 variable "region" {