gh-136728: Refactor build.yml CI config and multissltests.py

[hugovk]

Continuation of #136729.

Original description:

---

Notes

Please see #136728. Changes to build.yml are directly adapted from @hugovk's proof-of-concept here.

Testing

• this PR's CI
• PR CI on my fork.

• Issue: Refactor build.yml CI ssltests config and multissltests.py #136728

[webknjaz]

>- makes EOL escaping redundant while allowing for nice line separation of long/logically self-contained components:

Suggested change

	run: |
	env:
	CONFIGURE_TRAILING_ARGS: >-
	${{
	matrix.ssl != 'openssl'
	&& '--with-builtin-hashlib-hashes=blake2 --with-ssl-default-suites=openssl'
	|| ''
	}}
	run: >-

[picnixz]

I prefer \ becauseI find them easier to read. I find the >- harder to read honestly.

[webknjaz]

Suggested change

	CMD=(./configure CFLAGS="-fdiagnostics-format=json" --config-cache --enable-slower-safety --with-pydebug --with-openssl="$SSL_DIR")
	if [ "${{matrix.ssl }}" = "openssl" ]; then
	"${CMD[@]}"
	else
	"${CMD[@]}"--with-builtin-hashlib-hashes=blake2 --with-ssl-default-suites=openssl
	fi
	./configure
	CFLAGS="-fdiagnostics-format=json"
	--config-cache
	--enable-slower-safety
	--with-pydebug
	--with-openssl="$SSL_DIR"
	${CONFIGURE_TRAILING_ARGS}

[picnixz]

I prefer the if/else approach. I do not like the notion of 'trailing' args.

[picnixz]

So as I said previously, we should just have annotated properties. It will complain at runtime if we are missing one.

[hugovk]

Please could you make GH suggestions here, or a PR to my branch?

[picnixz]

I am sorry I am on mobile only (I am travelling) so I cannot do it easily :(

[hugovk]

No rush, it can wait!