After new feature implementation the default subject and message for all actions have been moved to media type message template except for Internal action. Because the Internal subject and message depend on operations: not supported trigger uses one text and macros, and not supported discovery rule uses different text and macros. 

But now we have an empty subject and message in the media type message template and also for build-in Internal Actions.

I suggest to return the subject and message text for built-in internal actions on page Configuration > Actions> Internal action. 

Steps to reproduce:

1. Open 4.0 zabbix version
2. Go to Configuration -> Actions-> Internal action
3. Open one of the three built-in actions, for example "Report not supported items"
4. Default subject with prepared text and useful macros
   {ITEM.STATE} : {HOST.NAME}:{ITEM.NAME}
5. Default message with prepared text and useful macros
   Host: {HOST.NAME}
   Item: {ITEM.NAME}
   Key: {ITEM.KEY}
   State: {ITEM.STATE}
6. Open 5.0+ zabbix version
7. Check one of the three built-in actions in Configuration > Actions> Internal action
8.  Go to Administration -> Media types and Create new media
9. Select Internal problem or Internal recovery in Message template tab

Result:
Empty subject and message
Expected:
Prepared subject and message text as in 4.0 version for built-in internal actions