Add enemy multiplier to regular survival

[(PSN)Nierou]

Railjack survivals feel terrible and it is often the case of there not being enough enemies to keep up life support, I haven't touched a regular survival in a long time and after doing railjack and Lua survival it's really bad. Making more enemies spawn would go a long way to solving the problem without really increasing the difficulty.

Low MR and other new players are able to handle sanctuary onslaught, in addition survival is just horribly boring early star chart due to lack of enemy density it was a real slog just doing 5 minutes to unlock all nodes.