Currently, tests use a handful of constants to determine how many
iterations to perform: `NTESTS`, `AROUND`, and `MAX_CHECK_POINTS`. This
configuration is not very straightforward to adjust and needs to be
repeated everywhere it is used.
Replace this with new functions in the `run_cfg` module that determine
iteration counts in a more reusable and documented way.
This only updates `edge_cases` and `domain_logspace`, `random` is
refactored in a later commit.
9a7a519370