CodeQL cleanup for alerts #18, #19, #20 (#4153)

Small cleanup PR to close three CodeQL alerts, without changing app
behavior.

-
[#18](https://github.com/MagicMirrorOrg/MagicMirror/security/code-scanning/18)
in `js/loader.js`
-
[#19](https://github.com/MagicMirrorOrg/MagicMirror/security/code-scanning/19)
in `js/socketclient.js`
-
[#20](https://github.com/MagicMirrorOrg/MagicMirror/security/code-scanning/20)
in `tests/electron/modules/calendar_spec.js`

For `Loader` and `MMSocket`, make the global export explicit via
`globalThis` (instead of suppressing `no-unused-vars`).
For calendar tests, remove the unused debug helper `logAllText`.
Also includes a tiny e2e cleanup: `MM_PORT` is cleared in `afterAll`.

Outcome: Three open CodeQL alerts are addressed with small, low-risk
changes. The global intent for `Loader` and `MMSocket` is explicit, dead
test helper code is removed, and e2e test state is cleaned up more
reliably between runs.

With this, all current [code scanning
issues](https://github.com/MagicMirrorOrg/MagicMirror/security/code-scanning)
should be resolved in the develop branch 🎈

js/socketclient.js

@@ -1,6 +1,5 @@
 /* global io */
 
-// eslint-disable-next-line no-unused-vars
 const MMSocket = function (moduleName) {
 	if (typeof moduleName !== "string") {
 		throw new Error("Please set the module name for the MMSocket.");
@@ -45,3 +44,5 @@ const MMSocket = function (moduleName) {
 		this.socket.emit(notification, payload);
 	};
 };
+
+globalThis.MMSocket = MMSocket;