[ISSUE] Configuration drift in databricks_cluster when is_single_node is set to true

[alexott]

The is_single_node represents a simpler way of configuring single node clusters, but it automatically adds necessary spark_conf and custom_tags values, leading to the configuration drift, like this:

  # databricks_cluster.single_node_new_1228_101700_uxdk2a63 will be updated in-place
  ~ resource "databricks_cluster" "single_node_new_1228_101700_uxdk2a63" {
      ~ custom_tags                  = {
          - "ResourceClass" = "SingleNode" -> null
        }
        id                           = "1228-102112-aco3jrk3"
      ~ spark_conf                   = {
          - "spark.databricks.cluster.profile" = "singleNode" -> null
          - "spark.master"                     = "local[*, 4]" -> null
        }
        # (19 unchanged attributes hidden)

        # (1 unchanged block hidden)
    }

for the following configuration:

resource "databricks_cluster" "single_node_new_1228_101700_uxdk2a63" {
  spark_version      = "15.4.x-scala2.12"
  single_user_name   = "[email protected]"
  runtime_engine     = "STANDARD"
  node_type_id       = "Standard_D4ds_v5"
  kind               = "CLASSIC_PREVIEW"
  is_single_node     = true
  data_security_mode = "SINGLE_USER"
  cluster_name       = "Single Node new (TF)"
  autotermination_minutes = 10
}