Only run systrace test on API 29+, avoid building scenario app for 28

.ci.yaml

@@ -89,7 +89,6 @@ targets:
     enabled_branches:
       - main
     recipe: engine_v2/engine_v2
-    bringup: true
     properties:
       config_name: linux_android_emulator
     timeout: 60

ci/builders/linux_android_emulator.json

@@ -80,8 +80,7 @@
             "ninja": {
                 "config": "android_debug_x86",
                 "targets": [
-                    "flutter/shell/platform/android:flutter_shell_native_unittests",
-                    "flutter/testing/scenario_app"
+                    "flutter/shell/platform/android:flutter_shell_native_unittests"
                 ]
             },
             "tests": [

testing/android_systrace_test.py

@@ -140,6 +140,17 @@ def main():
 
   args = parser.parse_args()
 
+  android_api_level = subprocess.check_output([
+      args.adb_path, 'shell', 'getprop', 'ro.build.version.sdk'
+  ],
+                                              text=True).strip()
+  if int(android_api_level) < 29:
+    print(
+        'Android API %s detected. This script requires API 29 or above.' %
+        android_api_level
+    )
+    return 0
+
   install_apk(args.apk_path, args.package_name, args.adb_path)
   start_perfetto(args.package_name, args.adb_path)
   launch_package(args.package_name, args.activity_name, args.adb_path)