Marks Mac_ios external_ui_integration_test_ios to be flaky (#106807)

diff --git a/.ci.yaml b/.ci.yaml
index 34ec913..cb0ebce 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -3255,6 +3255,7 @@
     scheduler: luci
 
   - name: Mac_ios external_ui_integration_test_ios
+    bringup: true # Flaky https://github.com/flutter/flutter/issues/106806
     recipe: devicelab/devicelab_drone
     presubmit: false
     timeout: 60