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/Declarations/UniqueParameterNames/tst.js

@@ -1,7 +1,7 @@
 function f(
-x,
 x, // $ Alert
-\u0078 // $ Alert
+x, // $ Alert
+\u0078
 ) { return; }
 
 this.addPropertyListener(prop.name, function(_, _, _, a) {