Deprecate disabling report_memleaks INI directive

[alexandre-daubois]

RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_the_report_memleaks_ini_directive

[TimWolla]

This formatting is inconsistent with the other deprecated options, please unify.

I also wonder if there still is value in having this option readily presented in the example INI files. It's deprecated and only affects a debug build. Perhaps we can just remove this entire block for improved DX? If we want to keep it, the INI should be commented, though (to make sure it uses the built-in default).

[alexandre-daubois]

I'd say it should be kept. It costs nothing and this will avoid making exceptions for certain settings. Maybe it could also be easier for maintainers when upmerging.

[ndossche]

I agree with Tim

[edorian]

RM wise: 👍 to merge this during beta, once the technical details are approved by others

[TimWolla]

Given the approvals and no other comments on #19481 (comment) I'm going ahead with merging. Should we decide to remove the INI from the example config, we can still do in a follow-up.

[nicolas-grekas]

In order to minimize the noise-level of the deprecation, the deprecation should be triggered only in DEBUG builds.
On non -DEBUG builds, this is already a no-op, so there's no need to annoy the community with it.