test(ios): revert to iPhone 16 + macos-15 + Xcode 16.4

there were severe performance problems with remote-config testing on
iPhone 17 + macos-26 + Xcode 26, perhaps this will help

Author: mikehardy

.github/workflows/tests_e2e_ios.yml

@@ -86,7 +86,7 @@ jobs:
   # it will run unit tests on whatever OS combinations are desired
   ios:
     name: iOS (${{ matrix.buildmode }}, ${{ matrix.iteration }})
-    runs-on: macos-26
+    runs-on: macos-15
     needs: matrix_prep
     # TODO matrix across APIs, at least 11 and 15 (lowest to highest)
     timeout-minutes: 70

tests/.detoxrc.js

@@ -48,7 +48,7 @@ module.exports = {
     simulator: {
       type: 'ios.simulator',
       device: {
-        type: 'iPhone 17',
+        type: 'iPhone 16',
       },
     },
     attached: {