Remove pauseTest workaround

Follows-up #497 which introduced
this because QUnit 2.8 didn't support changing an existing `assert.timeout()`
by calling it again in the same test (it would leave the old one unchanged,
and start a second timeout).

This was fixed in QUnit 2.9.3, released in Oct 2019.

The ember-qunit package declares a peer dependency on `qunit@2.13.0`,
which should remove the need for this workaround.

Ref #496.

addon/src/index.js

@@ -44,12 +44,6 @@ export function setupTest(hooks, _options) {
       let originalPauseTest = this.pauseTest;
       this.pauseTest = function QUnit_pauseTest() {
         assert.timeout(-1); // prevent the test from timing out
-
-        // This is a temporary work around for
-        // https://github.com/emberjs/ember-qunit/issues/496 this clears the
-        // timeout that would fail the test when it hits the global testTimeout
-        // value.
-        clearTimeout(QUnit.config.timeout);
         return originalPauseTest.call(this);
       };
     });