remove Mac_ios ios_app_with_extensions_test (#131806)

Removing the extension test that unnecessarily running with devices.

The new hostonly tests were added in https://github.com/flutter/flutter/pull/131441

.ci.yaml

@@ -3712,24 +3712,6 @@ targets:
         ["devicelab", "ios", "mac"]
       task_name: integration_ui_ios_textfield
 
-  - name: Mac_ios ios_app_with_extensions_test
-    recipe: devicelab/devicelab_drone
-    presubmit: false
-    timeout: 60
-    properties:
-      tags: >
-        ["devicelab", "ios", "mac"]
-      task_name: ios_app_with_extensions_test
-
-  - name: Mac_arm64_ios ios_app_with_extensions_test
-    recipe: devicelab/devicelab_drone
-    presubmit: false
-    timeout: 60
-    properties:
-      tags: >
-        ["devicelab", "ios", "mac", "arm64"]
-      task_name: ios_app_with_extensions_test
-
   - name: Mac_x64 ios_app_with_extensions_test
     recipe: devicelab/devicelab_drone
     presubmit: false
@@ -3742,7 +3724,6 @@ targets:
       tags: >
         ["devicelab", "hostonly", "mac"]
       task_name: ios_app_with_extensions_test
-    bringup: true
 
   - name: Mac_arm64 ios_app_with_extensions_test
     recipe: devicelab/devicelab_drone
@@ -3756,7 +3737,6 @@ targets:
       tags: >
         ["devicelab", "hostonly", "mac", "arm64"]
       task_name: ios_app_with_extensions_test
-    bringup: true
 
   - name: Mac_ios ios_content_validation_test
     recipe: devicelab/devicelab_drone