Merge release commits to 33.x

* Fix `Any` hasbit consistency issue in OSS.

`Any` `value` field is a `bytes` field in OSS, and since cl/792909628 (#22956), `_internal_mutable_*()` accessors for string fields don't set hasbits. This can cause the hasbit to be missing for the `value` field of `Any` after calling `PackFrom`, which will serialize incorrectly.

This change also includes fixes to `any_test`, which failed to catch this bug. We got unlucky, and every test which checked a roundtrip `PackFrom` -> `UnpackTo` for an `Any` field reused the same `Any` object, calling `MessageLite::ParseFromString` (which `Clear()`s it) on the same object. However, `Clear()` skips string fields whose hasbits are not set. This meant the `string value` field of the `Any` was not cleared, since its hasbit had not been properly set by `PackFrom`. So even though the `Any` value skipped serializing its value, the reused `Any` object still contained the expected `string value` serialization of the submessage, and `UnpackTo` worked correctly.

The culprit change was adopted in release 33.0, so it will need to be patched to this version.

See #24258.

Fixes #24258

PiperOrigin-RevId: 828299368

* update staleness

* Upgrade setup-php to speed up PHP tests

This build has become a severe bottleneck in our CI.  To avoid this in the future, always use whatever pre-install version is on the mac runners.  The linux tests will cover specific versions of PHP still.

PiperOrigin-RevId: 818864695

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Co-authored-by: Clayton Knittel <cknittel@google.com>
Co-authored-by: Mike Kruskal <mkruskal@google.com>

This matches our GeneratorNames APIs, and it's become clear that this information is necessary for certain classes of code-generators to be able to predict where our generated code will end up.

PiperOrigin-RevId: 829216363

Co-authored-by: Mike Kruskal <mkruskal@google.com>