chore(build): fix karma not exiting properly (#1741)

* Fixes the Karma tasks not exiting properly. This is an issue, because doing a keyboard interrupt doesn't stop the Gulp watchers that are going on in the background.
* Increase the time that Karma waits before starting to run tests. This should help mitigate the multiple reloads when running unit tests locally.

Related to #1681.

test/karma.config.ts

@@ -59,6 +59,7 @@ export function config(config) {
     colors: true,
     logLevel: config.LOG_INFO,
     autoWatch: true,
+    autoWatchBatchDelay: 500,
 
     sauceLabs: {
       testName: 'material2',