Remote command execution on Zabbix Agent, by Proxy, don't follow the manual when it say:

Remote commands on Zabbix agent are executed without timeout by the system.run[,*nowait*] key and are not checked for execution results.

https://www.zabbix.com/documentation/4.0/manual/config/notifications/action/operation/remote_command
As a matter of fact, if Remote commands execution on Zabbix Agent, by Proxy, remote commands are executed with timeout by the system.run[,wait]. 

Steps to reproduce:

1. Add a host Monitored by proxy
   
2. Actions -> Operations -> Operarion type [Remote command] -> Type[Custom script] -> Execute on [Zabbix agent]
   
3. Trigger an Action

Result:

• Refer to below debug log when Remote commands execution on Zabbix Agent, by Proxy

   26428:20200123:062020.292 Requested [system.run[#!/bin/bash
  export PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
  echo "start" >> /tmp/test
  date >> /tmp/test
  sleep 10
  echo "end" >> /tmp/end
  date >> /tmp/test,wait]]
  

• If not monitored by proxy, the manual makes sense

   21785:20200123:062215.586 Requested [system.run[#!/bin/bash
  export PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
  echo "start" >> /tmp/test
  date >> /tmp/test
  sleep 10
  echo "end" >> /tmp/end
  date >> /tmp/test,nowait]]
  

• Action log
  
  Expected:
  In the case of remote commands execution on Zabbix Agent, by Proxy,it should work like manual it says.