fix show -json tests

The prior state recorded in the plans did not match the actual prior
state. Make the plans and state match depending on whether there was
existing state or not.

command/testdata/show-json/basic-create/output.json

@@ -53,18 +53,7 @@
             ]
         }
     },
-    "prior_state": {
-        "format_version": "0.1",
-        "values": {
-            "outputs": {
-                "test": {
-                    "sensitive": false,
-                    "value": "bar"
-                }
-            },
-            "root_module": {}
-        }
-    },
+    "prior_state": {},
     "resource_changes": [
         {
             "address": "test_instance.test[0]",

command/testdata/show-json/basic-delete/terraform.tfstate

@@ -3,7 +3,12 @@
   "terraform_version": "0.12.0",
   "serial": 7,
   "lineage": "configuredUnchanged",
-  "outputs": {},
+  "outputs": {
+    "test": {
+      "value": "bar",
+      "type": "string"
+    }
+  },
   "resources": [
     {
       "mode": "managed",

command/testdata/show-json/basic-update/terraform.tfstate

@@ -3,7 +3,12 @@
     "terraform_version": "0.12.0",
     "serial": 7,
     "lineage": "configuredUnchanged",
-    "outputs": {},
+    "outputs": {
+        "test": {
+            "value": "bar",
+            "type": "string"
+        }
+    },
     "resources": [
         {
             "mode": "managed",

command/testdata/show-json/modules/output.json

@@ -69,18 +69,7 @@
             ]
         }
     },
-    "prior_state": {
-        "format_version": "0.1",
-        "values": {
-            "outputs": {
-                "test": {
-                    "sensitive": false,
-                    "value": "baz"
-                }
-            },
-            "root_module": {}
-        }
-    },
+    "prior_state": {},
     "resource_changes": [
         {
             "address": "module.module_test_bar.test_instance.test",

command/testdata/show-json/multi-resource-update/output.json

@@ -101,20 +101,14 @@
         "format_version": "0.1",
         "terraform_version": "0.13.0",
         "values": {
-            "outputs": {
-                "test": {
-                    "sensitive": false,
-                    "value": "bar"
-                }
-            },
             "root_module": {
                 "resources": [
                     {
                         "address": "test_instance.test[0]",
+                        "index": 0,
                         "mode": "managed",
                         "type": "test_instance",
                         "name": "test",
-                        "index": 0,
                         "provider_name": "registry.terraform.io/hashicorp/test",
                         "schema_version": 0,
                         "values": {