refactor(tests): remove unnecessary onload callback in JSDOM setup

The onload callback in getDocument() was no longer needed since
global.document is set immediately after JSDOM creation. Removing
it simplifies the code and makes tests run faster.

Author: KristjanESPERANTO

tests/e2e/helpers/global-setup.js

@@ -105,9 +105,7 @@ exports.getDocument = () => {
 				useragent: "node.js"
 			};
 			dom.window.fetch = fetch;
-			dom.window.onload = () => {
-				resolve();
-			};
+			resolve();
 		});
 	});
 };