build: remove iOS test runs

Removes the tests that run against iOS. There are a couple of reasons to do so:
* The tests haven't caught any issues in years.
* The tests tend to be flaky.
* They're running aginst iOS 15 which Angular no longer supports. We can't update to anything newer, because we would have to update our Saucelabs setup which will require dev infra time investment.

Author: crisbeto

test/browser-providers.js

@@ -5,7 +5,6 @@
  *   - `saucelabs`: Launches the browser within Saucelabs
  */
 const browserConfig = {
-  'iOS15': {unitTest: {target: 'saucelabs'}},
   'Safari16': {unitTest: {target: 'browserstack'}},
 };
 

test/karma-browsers.json

@@ -1,13 +1,4 @@
 {
-  "SAUCELABS_IOS15": {
-    "base": "SauceLabs",
-    "appiumVersion": "1.22.0",
-    "deviceOrientation": "portrait",
-    "browserName": "Safari",
-    "platformVersion": "15.0",
-    "platformName": "iOS",
-    "deviceName": "iPhone 13 Pro Max Simulator"
-  },
   "BROWSERSTACK_SAFARI16": {
     "base": "BrowserStack",
     "browser": "Safari",