evalv3 does not obey CUE_DEBUG_SORT_ARCS=2 like the default evaluator

[mvdan]

$ cue version
cue version v0.11.0-alpha.1.0.20240920112956-687464eb1846+dirty

go version devel go1.24-165bf241f2 2024-09-19 00:40:50 +0000
      -buildmode exe
       -compiler gc
  DefaultGODEBUG asynctimerchan=1,gotypesalias=0,httpservecontentkeepheaders=1,multipathtcp=0,randseednop=0,tls3des=1,tlskyber=0,x509keypairleaf=0,x509negativeserial=1
     CGO_ENABLED 1
          GOARCH amd64
            GOOS linux
         GOAMD64 v3
             vcs git
    vcs.revision 687464eb1846e51628bb62e8e8804968bd300d69
        vcs.time 2024-09-20T11:29:56Z
    vcs.modified true
cue.lang.version v0.11.0

I would expect the following testscript to succeed:

env CUE_DEBUG_SORT_ARCS=2

env CUE_EXPERIMENT=
exec cue export
cmp stdout out.gold

env CUE_EXPERIMENT=evalv3
exec cue export
cmp stdout out.gold

-- file.cue --
package p

x: [_]: set: [string]: bool

x: [_]: {
	set: "aaa": true
	set: "zzz": true

	// Note that this bug depends on this field name sorting before the other.
	asList: [for p, _ in set {p}]
}

x: image1: set: ddd: true
-- out.gold --
{
    "x": {
        "image1": {
            "asList": [
                "aaa",
                "ddd",
                "zzz"
            ],
            "set": {
                "aaa": true,
                "ddd": true,
                "zzz": true
            }
        }
    }
}

However, it fails:

> env CUE_EXPERIMENT=evalv3
> exec cue export
[stdout]
{
    "x": {
        "image1": {
            "asList": [
                "ddd",
                "aaa",
                "zzz"
            ],
            "set": {
                "aaa": true,
                "ddd": true,
                "zzz": true
            }
        }
    }
}
> cmp stdout out.gold
diff stdout out.gold
--- stdout
+++ out.gold
@@ -2,8 +2,8 @@
     "x": {
         "image1": {
             "asList": [
-                "ddd",
                 "aaa",
+                "ddd",
                 "zzz"
             ],
             "set": {

FAIL: repro-evalv3.txtar:9: stdout and out.gold differ

evalv3 fails to sort the fields when looping in the list comprehension, so we get a non-sorted result.