don't restart renderer in SV_SpawnServer

The renderer restart in SV_SpawnServer doesn't appear to do anything. As per https://github.com/ioquake/ioq3/blob/master/code/client/cl_scrn.c#L494, the connect screen isn't rendered until the UI VM is loaded anyways, at which point the renderer would have restarted again due to CL_FlushMemory being called once the gamestate is parsed. I throttled the connection process to validate this while loading a map.

Furthermore (and the reason I changed this in the first place) restarting the renderer here leaves the hunk memory it allocates trapped under the mark set at the bottom of SV_SpawnServer (https://github.com/ioquake/ioq3/blob/master/code/server/sv_init.c#L615).