Fix callout json plugin show global stats (#43123)

* fix callback Plugin json to support global stat set by set_stats module

* refactor to not break compatiblity, add trailing comma on output dict

* Remove sorted, as it not needed

* refactor, to sivels better code

* clean some code messup

* add changelog fragment

* added missing new line

* fix pep8 stuff

changelogs/fragments/43123-add_support_for_per_host_no_stats.yaml

@@ -0,0 +1,3 @@
+---
+minor_changes:
+  - Add support for per_host:no stats for the callback plugin **json** (https://github.com/ansible/ansible/pull/43123)

lib/ansible/plugins/callback/json.py

@@ -101,14 +101,17 @@ class CallbackModule(CallbackBase):
             summary[h] = s
 
         custom_stats = {}
+        global_custom_stats = {}
+
         if self.get_option('show_custom_stats') and stats.custom:
             custom_stats.update(dict((self._convert_host_to_name(k), v) for k, v in stats.custom.items()))
-            custom_stats.pop('_run', None)
+            global_custom_stats.update(custom_stats.pop('_run', {}))
 
         output = {
             'plays': self.results,
             'stats': summary,
             'custom_stats': custom_stats,
+            'global_custom_stats': global_custom_stats,
         }
 
         self._display.display(json.dumps(output, indent=4, sort_keys=True))