Server RAM grows to the limits during `symbolic-args-fail.main` proof

[jberthold]

An interim-simplification option was added to the server to work around a problem with symbolic-args-fail.main.
Without adding that, the server would grow an enormous memory footprint during the proof. I experimented with the request in question but could not find out where exactly the memory is allocated. It is not Haskell heap data, so probably the LLVM backend allocates it somehow.

Originally posted by @jberthold in #625 (comment)