fmt: use get_matches_from() instead of try_get_matches_from() in tests

[cakebaker]

While reviewing #6362 I noticed that we use try_get_matches_from() in the tests. We pass only valid values to this function, and so it's simpler to use get_matches_from().

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[BenWiederhake]

Yes, the code is much easier to read.

However, when an unexpected failure occurs, this now kills the entire test suite due to the direct invocation of exit(2), instead of just showing an error for that single testcase.

Suggestion: Mostly your approach, but with try_get_matches_from(…).unwrap()
This way, the testcase fails, and we get a "normal" testcase failure (and all other tests continue as usual).

[cakebaker]

Changes since last push:

• used try_get_matches_from(…).unwrap() instead of get_matches_from (thanks to @BenWiederhake for the suggestion)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[BenWiederhake]

Simplifies the code, has no disadvantage that I can think of. Yay! :D

EDIT: CI failures are #6275 and #6333, as usual.