ci: Follow-up CI patches

Hi,

Andres shared some CI patches in the 'Heads Up: cirrus-ci is shutting
down June 1st' thread [1]. Since this thread is already quite long, I
wanted to create a new thread for them.

There were 9 patches in the thread and 3 of them already committed:

- 0001-ci-Generate-crashlogs-on-Windows.patch: Committed at d374280e183.

- 0002-ci-Use-meson-for-most-of-CompilerWarnings-it-s-.patch:
Committed at 3ca57291ff.

- 0006-ci-Use-optimized-build-for-mingw.patch: Committed at 4075409de0.

----------

These are the uncommitted patches, I rebased them with small changes:

- 0003-ci-Make-msys2-install-smaller.patch

No functional changes; the commit message is updated (where -> were).

- 0004-ci-Make-our-own-msys2-install-from-scratch-inst.patch

'msys2/setup-msys2(at)66cd2cce69caa17b53920067426061ca1de3a884 # v2.31.1'
this SHA points to v2.32.0, it is fixed. Also Jacob's
```
Can we just get rid of the MSYSTEM envvar now? (And the
MSYS2_PATH_TYPE, if we replace it with `path-type: inherit` in the
action parameters?) See attached -0011.
```
comment [2] is applied.

- 0005-squash-or-drop-Use-pacboy-for-shorter-package-n.patch

No change. I lean toward dropping this because explicitly naming
packages makes it easier to search if something goes wrong. Jacob said
it looks nicer with this change [3].

- 0007-ci-get-build-test-concurrency-from-environment.patch

I used %NUMBER_OF_PROCESSORS% instead of 'bash -c nproc' to not depend
on bash.

- 0008-ci-Make-runs-on-overridable.patch

Separatd MacPorts caches by runner architecture to avoid restoring
incompatible binaries when changing runners.

- 0009-ci-Move-to-per-job-naming-for-containers.patch

Removed 'options: *linux_container_options' from CompilerWarnings
since it is not used.
----------

Rebased and updated patches are attached. Order of the patches has
changed because I got them from Andres' working repository. I CCed
people from the [1] thread.

[1] https://postgr.es/m/iggjozfshwbqpv33x5jqwtju5k5zrkyu3257dlifxkhtpg7eoq%40k2ccyrdi5dtu
[2] https://postgr.es/m/CAOYmi%2BkOGycb6Vw-Z19%3DM8js6d36%3D6%3DkUw4Cu5%2BueQej77ig%2Bg%40mail.gmail.com
[3] https://postgr.es/m/CAOYmi%2BnEqAYKjh1r7HiKQ%3DLhFU5LMHw%3DXHuEkUr9We6b0judsg%40mail.gmail.com

--
Regards,
Nazir Bilal Yavuz
Microsoft