Make tests take less than forever to finish

[effectfully]

plutus-core-test takes 12 seconds to run
untyped-plutus-core-test takes 2 minutes and 36 seconds to run. Most of that seems to be spent on the freshly added bitwise primitives.

We have the nightly test suite (example) for squeezing the juice out of CI, so we shouldn't do that for each developer machine.

Here are two places where we definitely should tweak how many tests are run: 1 and 2), but there are likely more of them, we just need to look at the console output of a test run and tweak anything that takes more than a few seconds.