`misc/invalid-opt.pl` is missing on test coverage page

[cakebaker]

While looking at #6657 I noticed that misc/invalid-opt.pl is missing on our test coverage page.

[sylvestre]

bizarre:

./util/remaining-gnu-error.py|grep misc/invalid-opt.pl
../gnu/tests/misc/invalid-opt.pl: 2157

[sylvestre]

here is why:
https://github.com/uutils/coreutils/blob/main/util/build-gnu.sh#L177