JS: Move some alerts to their correct location

One of the diffs look confusing but:
Previously parameter {2,3} where flagged, now parameter {1,2} are flagged.

Note that for command injection, the SystemCommandExecution is flagged
despite the test file claiming otherwise.

javascript/ql/test/query-tests/Statements/SuspiciousUnusedLoopIterationVariable/tst.js

@@ -1,6 +1,6 @@
-function countOccurrences(xs, p) { // $ Alert
+function countOccurrences(xs, p) {
 	var count = 0;
-	for (let x of xs)
+	for (let x of xs) // $ Alert
 		if (p())
 			++count;
 	return count;