[Android benchmark] Increase cool down time to 180 (pytorch#9480)

Let's see if it can make things more stable!

Author: kirklandsign

extension/benchmark/android/benchmark/android-llm-device-farm-test-spec.yml.j2

@@ -111,7 +111,7 @@ phases:
 
         adb -s $DEVICEFARM_DEVICE_UDID shell dumpsys deviceidle force-idle
         adb -s $DEVICEFARM_DEVICE_UDID shell dumpsys deviceidle unforce
-        adb -s $DEVICEFARM_DEVICE_UDID shell sleep 30
+        adb -s $DEVICEFARM_DEVICE_UDID shell sleep 180
 
         if [ -n "$BIN_FOUND" ]; then
           adb -s $DEVICEFARM_DEVICE_UDID shell am start -W -n org.pytorch.minibench/.LlmBenchmarkActivity \