ci: temporarily disable Android 10 browser unit tests on Saucelabs (angular#37399)

Disabling Android 10 browser unit tests on Saucelabs due to errors.

After remediation from Saucelabs to correct the discovered failures, this change can be reverted to renable the tests on Android 10.

Example of failures seen:

```
02 06 2020 14:03:05.048:INFO [SaucelabsLauncher]: Chrome 10.0 (Android) session at https://saucelabs.com/tests/54f5fb181db644a3b4779187c2309000

02 06 2020 14:03:06.869:INFO [Chrome Mobile 74.0.3729 (Android 0.0.0)]: Disconnected browser returned on socket E-bi0p0NKtghk-HcAAAO with id 85563367.

Chrome Mobile 74.0.3729 (Android 0.0.0) ERROR: Error: XHR error loading http://angular-ci.local:9876/base/node_modules/rxjs/internal/operators/zip.js

	Error loading http://angular-ci.local:9876/base/node_modules/rxjs/internal/operators/zip.js as "../internal/operators/zip" from http://angular-ci.local:9876/base/node_modules/rxjs/operators/index.js

Error: XHR error loading http://angular-ci.local:9876/base/node_modules/rxjs/internal/operators/zip.js

    at error (http://angular-ci.local:9876/base/node_modules/systemjs/dist/system.src.js?1c6a6c12fec50a8db7aeebe8e06e2b70135c0615:1028:16)

    at XMLHttpRequest.xhr.onreadystatechange [as __zone_symbol__ON_PROPERTYreadystatechange] (http://angular-ci.local:9876/base/node_modules/systemjs/dist/system.src.js?1c6a6c12fec50a8db7aeebe8e06e2b70135c0615:1036:13)

    at XMLHttpRequest.wrapFn (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:809:43)

    at ZoneDelegate.invokeTask (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:432:35)

    at Zone.runTask (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:201:55)

    at ZoneTask.invokeTask [as invoke] (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:514:38)

    at invokeTask (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:1722:18)

    at XMLHttpRequest.globalZoneAwareCallback (http://angular-ci.local:9876/base/dist/bin/packages/zone.js/npm_package/dist/zone.js?942d01da94828e1c75e8527fa8d06f363d6379ce:1748:21)
```

PR Close angular#37399

Author: josephperrott

browser-providers.conf.js

@@ -31,7 +31,16 @@ var CIconfiguration = {
   'Android7': {unitTest: {target: 'SL', required: true}, e2e: {target: null, required: true}},
   'Android8': {unitTest: {target: 'SL', required: true}, e2e: {target: null, required: true}},
   'Android9': {unitTest: {target: 'SL', required: true}, e2e: {target: null, required: true}},
-  'Android10': {unitTest: {target: 'SL', required: true}, e2e: {target: null, required: true}},
+  // Disable Android 10 tests due to infrastructure failure.
+  // ex:
+  // Chrome Mobile 74.0.3729 (Android 0.0.0) ERROR:
+  //    Error: XHR error loading
+  //    http://angular-ci.local:9876/base/node_modules/rxjs/internal/operators/zip.js
+  //
+  // Error loading http://angular-ci.local:9876/base/node_modules/rxjs/internal/operators/zip.js as
+  // "../internal/operators/zip" from
+  // http://angular-ci.local:9876/base/node_modules/rxjs/operators/index.js
+  'Android10': {unitTest: {target: 'SL', required: false}, e2e: {target: null, required: true}},
   // Disable all Safari and iOS tests because of incorrect results
   // ex:
   // Mobile Safari 13.0.0 (iOS 13.0.0) styling static template only should capture static values in