tests: Remove assertArraysEqual()

It is tied to the legacy jsUnit framework and now unused.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3164>

tests/common/assertions.js

@@ -1,15 +0,0 @@
-const JsUnit = imports.jsUnit;
-
-/**
- * Asserts if two arrays have the same length and each element passes assertEquals
- *
- * @template T
- * @param {string} errorMessage an error message if the arrays are not equal
- * @param {T[]} array1 the first array
- * @param {T[]} array2 the second array
- */
-export function assertArrayEquals(errorMessage, array1, array2) {
-    JsUnit.assertEquals(`${errorMessage} length`, array1.length, array2.length);
-    for (let j = 0; j < array1.length; j++)
-        JsUnit.assertEquals(`${errorMessage} item ${j}`, array1[j], array2[j]);
-}