builtins: skip TestSerialNormalizationWithUniqueUnorderedID under dea…

…dlock

This test is extremely slow -- it takes ~30s to run normally. The
addition of test-only verification pushed it over the edge, such that
running it under the deadlock detector would cause spurious failures,
so we skip it.

Closes #115541
Release note: None

pkg/sql/sem/builtins/builtins_test.go

@@ -241,6 +241,7 @@ func TestSerialNormalizationWithUniqueUnorderedID(t *testing.T) {
 
 	skip.UnderRace(t, "the test is too slow and the goodness of fit test "+
 		"assumes large N")
+	skip.UnderDeadlock(t, "the test is too slow")
 
 	ctx := context.Background()