[Epic] Tests improvements

[effectfully]

This issue is for dumping all the plans regarding tests improvements in a largely unstructured way.

[effectfully]

• [ ] discardIfAnyConstant (not . isSerialisable) $ Generators.genProgram @DefaultFun potentially wastes a lot of time discarding generated programs. discardIfAnyConstant is used in quite a few places
• [ ] Evaluation.Builtins.Definition should demand that each built-in function is unit-tested
• [ ] remove ignoreTest from Plutus IR tests by fixing the tests
• [ ] increase the number of test runs in Plutus IR from no to some (i.e. fix withMaxSuccess 0) for failing shrinking tests by figuring out why they are taking too long and fixing that
• [ ] can we somehow ban running 100 tests altogether? So that the number of tests to run is always explicitly specified