Change iOS device used by integration tests to iphone8, version 11.4

FTL experiencing internal issues on later devices.

Author: anonymous-akorn

.github/workflows/cpp-packaging.yml

@@ -667,8 +667,8 @@ jobs:
       apis: admob,analytics,auth,database,dynamic_links,firestore,functions,instance_id,messaging,remote_config,storage
       android_device: flame
       android_api: 29
-      ios_device: iphone11pro
-      ios_version: 13.3
+      ios_device: iphone8
+      ios_version: 11.4
     steps:
     - name: Checkout repo
       uses: actions/checkout@v2.3.1

.github/workflows/integration_tests.yml

@@ -27,10 +27,10 @@ on:
         default: '29'
       ios_device:
         description: 'iOS device model'
-        default: 'iphone11pro'
+        default: 'iphone8'
       ios_version:
         description: 'iOS device version'
-        default: '13.3'
+        default: '11.4'
 
 jobs:
   # To feed input into the job matrix, we first need to convert to a JSON