MQE: fix incorrect query results or "found duplicate series for the m…

…atch group" errors when binary operation has unsorted labels in `on`

pkg/streamingpromql/operators/vector_vector_binary_operation.go

@@ -402,6 +402,8 @@ func (b *VectorVectorBinaryOperation) groupKeyFunc() func(labels.Labels) []byte
 	buf := make([]byte, 0, 1024)
 
 	if b.VectorMatching.On {
+		slices.Sort(b.VectorMatching.MatchingLabels)
+
 		return func(l labels.Labels) []byte {
 			return l.BytesWithLabels(buf, b.VectorMatching.MatchingLabels...)
 		}

pkg/streamingpromql/testdata/ours/binary_operators.test

@@ -98,11 +98,21 @@ eval range from 0 to 24m step 6m left_side - on(env, pod) right_side
   {env="test", pod="a"} -9 -18 -27
   {env="test", pod="b"} -36 -45 -54
 
+eval range from 0 to 24m step 6m left_side - on(pod, env) right_side
+  {env="prod", pod="a"} -63 -72 -81
+  {env="test", pod="a"} -9 -18 -27
+  {env="test", pod="b"} -36 -45 -54
+
 eval range from 0 to 24m step 6m left_side - ignoring(env, pod) right_side
   {group="baz"} -33 -42 -51
   {group="bar"} -6 -15 -24
   {group="foo"} -69 -78 -87
 
+eval range from 0 to 24m step 6m left_side - ignoring(pod, env) right_side
+  {group="baz"} -33 -42 -51
+  {group="bar"} -6 -15 -24
+  {group="foo"} -69 -78 -87
+
 clear
 
 # One-to-one matching, but different series match at different time steps, or not at all