Service fails in Stop Timeout when configured with "Delegate=true" parameter

Issue

• Service is taking too much time to restart.
• There is a bug in service stopping when Delegate=true and kill mode is set to KillMode=mixedthen systemd will send the signals (TERM to the main process and KILL to all other processes) but wait until TimeoutStopSec occurs for no reason and at the end it will report a failure despite no process is still living.