ci: convert "pedantic" job into full build with breaking changes

ci: convert "pedantic" job into full build with breaking changes

The "pedantic" CI job is building on Fedora with `DEVOPTS=pedantic`.
This build flag doesn't do anything anymore starting with 6a8cbc41ba
(developer: enable pedantic by default, 2021-09-03), where we have
flipped the default so that developers have to opt-out of pedantic
builds via the "no-pedantic" option. As such, all this job really does
is to do a normal build on Fedora, which isn't all that interesting.

Convert that job into a full build-and-test job that uses Meson with
breaking changes enabled. This plugs two gaps:

  - We now test on another distro that we didn't run tests on
    beforehand.

  - We verify that breaking changes work as expected with Meson.

Furthermore, in a subsequent commit we'll modify both jobs that use
breaking changes to also enable Rust. By converting the Fedora job to
use Meson, we ensure that we test our Rust build infrastructure for both
build systems.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>