Avoid deleting server-info file if cleanup_on_exit=False is passed to launch_fluent

[mkundu1]

I think the server-info file should not be deleted if the argument cleanup_on_exit=False is passed to launch_fluent. This will help triaging issues related to port-setup when the client-server connection fails after launching Fluent. When Fluent is manually exited after launched via launch_fluent(..., cleanup_on_exit=False), the server-info file will be automatically deleted by Fluent (please confirm the behaviour).

[prmukherj]

In Fluent we can also write where the server info file has been written by the server.