remove default for Fleet membership_type

Author: anthonyrtong

mmv1/third_party/terraform/services/container/resource_container_cluster.go.tmpl

@@ -2453,7 +2453,6 @@ func ResourceContainerCluster() *schema.Resource {
 						"membership_type": {
 							Type:         schema.TypeString,
 							Optional:     true,
-							Default:      "MEMBERSHIP_TYPE_UNSPECIFIED",
 							ValidateFunc: validation.StringInSlice([]string{"MEMBERSHIP_TYPE_UNSPECIFIED", "LIGHTWEIGHT"}, false),
 							Description:  `The type of the cluster's fleet membership.`,
 							DiffSuppressFunc: tpgresource.EmptyOrDefaultStringSuppress("MEMBERSHIP_TYPE_UNSPECIFIED"),