Restart from Admin Center race condition on Windows

When restarting from the admin center, Nuxeo runs a launcher process with "restartbg".
The launcher tries to stop the server cleanly, and if the process sticks around for too long (STOP_MAX_WAIT) will call processManager.kill.
The ProcessManager class is the one from jodconverter. On Windows, it calls the taskkill command with a "/t" parameter, this terminates a process and all its children.
Unfortunately, in this case, the launcher process is itself a child of the nuxeo process, so it is terminated along with the server, which means the server is never restarted.

Short term: increase STOP_MAX_WAIT. This doesn't fix the race condition, just makes it less likely to occur.
Longer term: rewrite the ProcessManager to make it more discerning in what it chooses to kill.