Replace return; yield with yield from []

This has the same effect, but looks less hacky and makes PHPStan happy.
https://phpstan.org/r/df7fcc88-1df8-428e-b675-5dc6965c34d6

Previously this was needed to work properly with output capturing.

tests/Node/BlockTest.php

@@ -40,7 +40,7 @@ public function block_foo(array \$context, array \$blocks = []): iterable
 {
     \$macros = \$this->macros;
     yield "foo";
-    return; yield '';
+    yield from [];
 }
 EOF
             , new Environment(new ArrayLoader()),