Put back physiterations to 4, true default value

I checked the default value, it's 4, not 2. A value of 2 is causing issue with physics while running complex builds' physics, a value of 4 fixes it.
To check the default value, input gmod_physiterations into your gmod console

gmod_physiterations
"gmod_physiterations" = "2" (def. 4)

GarrysMod/cfg/lgsm-default.cfg

@@ -38,7 +38,7 @@ sv_allow_wait_command 0
 sv_allow_voice_from_file 0
 sv_turbophysics 0
 sv_max_usercmd_future_ticks 12
-gmod_physiterations 2
+gmod_physiterations 4
 sv_client_min_interp_ratio 1
 sv_client_max_interp_ratio 2
 think_limit 20