Remove the liquid_loop_max setting which should not be needed and essentially causes a memory leak

The liquid_loop_max setting is practically never adjusted by users, and there is also no practical way of figuring out a value to adjust it to. liquid_loop_max was intended to provide smoothing for large bursts of queued liquid updates to keep the server's step interval less spiky, but it is quite useless in its current state.

When this setting has a value that is too low, a memory leak can appear due to more stuff going into the queue than being read out from it. This has been noticed by @Zeno- and some other people.

Later some kind of auto-adjusted smoothing should be added that does not need configuration based on parameters that cannot even be looked up from anywhere.

Also, later some kind of a denial-of-service time limit for the liquid processing loop should be added, which, when triggered, will just delete the queue content without attempting to process it.