[GIT-PULLS] [php-src] PR #23302: Fix GH-23301: nested "yield from" yields a value twice when the middle generator ends with "yield from []"

Pull Request: https://github.com/php/php-src/pull/23302
Author: lazerg

GH-15375's fix made the `DO_INIT` re-advance guard in `zend_generator_resume()` read the flag from the delegating generator rather than from `orig_generator`. That flag is set by `zend_generator_yield_from()` and only ever cleared on `orig_generator`, so on a middle generator it stays set for the rest of its life.

When such a middle generator then delegates to a non-generator iterable (`yield from []`), it still sits on a `ZEND_YIELD_FROM` opline, so it is picked as the delegator even though no new generator link was established, and its stale `DO_INIT` suppresses the resume. The value it yielded last is presented a second time. Twig hits this on every template, since `doDisplay()` always ends with `yield from [];`.

Only treat the generator as the delegator when it actually delegated to another generator (`node.parent` is set); otherwise keep `orig_generator` as before. The GH-15375 tests still pass.

Fixes GH-23301