fix: foreach should not break init backtracking with DUPN (#3266)

Simplifies the compilation of `foreach` to avoid the problem in #3227 by
removing unnecessary `FORK ... BACKTRACK`.

Does not address `reduce`, which is less trivial.

tests/jq.test

@@ -2319,3 +2319,11 @@ try ltrimstr("x") catch "x", try rtrimstr("x") catch "x" | "ok"
 try ["OK", setpath([[1]]; 1)] catch ["KO", .]
 []
 ["KO","Cannot update field at array index of array"]
+
+# regression test for #3227
+foreach .[] as $x (0, 1; . + $x)
+[1, 2]
+1
+3
+2
+4