[spectec] Interpreter test expectations interfere with test suite additions

[rossberg]

With SpecTec on the main repo, the test suite can now be updated by other than SpecTec devs. Unfortunately, each time that happens, it breaks the SpecTec interpreter's test expectations as currently set up, and it requires spurious changes like this to fix after the fact.

@f52985, can we tweak the interpreter output such that the addition of new successful tests creates no diff? For example, only output the count statistics when it is not 100%.

[f52985]

Resolved by #2015, which removes the printed message for success rate.