Remove debug @shows in tests

[giordano]

Ref: #52750 (comment)

[DilumAluthge]

Could we convert these to test contexts (the feature that @Keno added)? So then they get hidden if the tests pass, but they get printed if the tests fail.

[giordano]

Could we convert these to test contexts

I don't see how, as they are in the source code of packages compiled in a subprocess, they aren't variables in the same scope as the tests.