test(internal/postprocessor): skip test that expects certain live config (googleapis#13090)

Librarian migrations have broken another test. Skip this one for the
time being, as the expectation it will go away when migrations are
complete.

Fixes: googleapis#13055

Author: shollyman

internal/postprocessor/main_test.go

@@ -51,6 +51,7 @@ func TestMain(m *testing.M) {
 }
 
 func TestProcessCommit(t *testing.T) {
+	t.Skip("test based on implicit config expectations")
 	tests := []struct {
 		name         string
 		title        string