AndroidTestUtilities: fix cleanup operation
`su` is not available by default on all devices: ``` > adb shell "echo ls /data/local/tmp | su" /system/bin/sh: su: not found > echo $? 0 ``` Also since `execute_adb_command` use `execute_process` under the hood the pipeline (`|`) will not be treated as special symbol and will be process just like one more command line argument for the `adb`.