CI: don't explicitly pick "bash" shell outside of Windows, fix regression

CI: don't explicitly pick "bash" shell outside of Windows, fix regression

When the "js/ci-github-workflow-markup" topic was originally merged in
[1] it included a change to get rid of the "ci/print-test-failures.sh"
step[2]. This was then brought back in [3] as part of a fix-up patches
on top[4].

The problem was that [3] was not a revert of the relevant parts of
[2], but rather copy/pasted the "ci/print-test-failures.sh" step that
was present for the Windows job to all "ci/print-test-failures.sh"
steps. The Windows steps specified "shell: bash", but the non-Windows
ones did not.

This broke the "ci/print/test-failures.sh" step for the "linux-musl"
job, where we don't have a "bash" shell, just a "/bin/sh" (a
"dash"). This breakage was reported at the time[5], but hadn't been
fixed.

It would be sufficient to change this only for "linux-musl", but let's
change this for both "regular" and "dockerized" to omit the "shell"
line entirely, as we did before [2].

Let's also change undo the "name" change that [3] made while
copy/pasting the "print test failures" step for the Windows job. These
steps are now the same as they were before [2], except that the "if"
includes the "env.FAILED_TEST_ARTIFACTS" test.

1. fc5a070f591 (Merge branch 'js/ci-github-workflow-markup', 2022-06-07)
2. 08dccc8fc1f (ci: make it easier to find failed tests' logs in the
   GitHub workflow, 2022-05-21)
3. 5aeb145780f (ci(github): bring back the 'print test failures' step,
   2022-06-08)
4. d0d96b8280f (Merge branch 'js/ci-github-workflow-markup', 2022-06-17)
5. https://lore.kernel.org/git/220725.86sfmpneqp.gmgdl@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>