Marks Windows flutter_tool_startup__windows to be unflaky (#112092)

diff --git a/.ci.yaml b/.ci.yaml
index 410fe26..bf91d20 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -4485,7 +4485,6 @@
       task_name: windows_startup_test
 
   - name: Windows flutter_tool_startup__windows
-    bringup: true
     recipe: devicelab/devicelab_drone
     presubmit: false
     timeout: 60