Run test subprocesses without shell

[NickSdot]

Extracted from #22917.

Runs eligible test, SKIPIF, and CLEAN subprocesses through structured proc_open() commands instead of a shell. This avoids shell parsing and Windows cmd.exe launch overhead; tests requiring shell semantics are unchanged.

This is actually more like a prerequisite for the rest, but has performance gain as well.

Result

Values in seconds; measured on macOS.

mode	master	this PR	saved	speedup
-j1	368.084	341.594	26.490	1.08×
-j10	64.496	55.843	8.653	1.15×

Reproduction:

Run on master and this PR:

nice -n 10 sapi/cli/php -n run-tests.php -n -q -j1 Zend/tests
nice -n 10 sapi/cli/php -n run-tests.php -n -q -j10 Zend/tests

[arnaud-lb]

Representing commands as arrays is a good idea in general, and the speed up from the reduced overhead is nice.

However, can we always do that, and always skip the shell? Otherwise we are increasing complexity.

[NickSdot]

Representing commands as arrays is a good idea in general, and the speed up from the reduced overhead is nice.

However, can we always do that, and always skip the shell? Otherwise we are increasing complexity.

Did as good as possible. Naturally this widened scope and hence diff churn. Either it's just fine as is (diff churn wise) or we cherry the last commit in yet another PR.

always skip the shell?

We still need create_shell_invocation() for --ARGS-- or we would have to parse it. I don't see the win. Please let's see that out of scope here. The whole thing ideally needs as split first (#22961), and then a cleanup. Let's decide that later.

[arnaud-lb]

This looks great!

Just two minor comments. I will merge once these are resolved.

Feel free to add a NEWS entry

[NickSdot]

c36e664 reverts some of the previously commit changes because of the CI failure. No other idea for that unless, as said earlier, we would parse --ARGS-- ourselves. If CI passes now I'd say we call it done; really don't want to open that file again before it is split up. 😵‍💫

Edit:
--ARGS-- should IMO use something like the below. Is there any reason to not do that? It's under 20 tests using that section/feature. Seems like complexity for little added value.

--ARGS--
['--yoo', '--ayy']

[NickSdot]

Got it back passing on Windows; CI is green.

Aside: I had edited the test matrix to only run Windows tests while debugging, that added the CI label and is probably why Tim was requested as reviewer. The edit that triggered it is already reverted.