[dogfooding][cleanup] Use static inner class clean up for test
code

Using this cleanup brings:
- It reviews the feature
 - For optimization: small memory usage reduction as the outer pointer
is removed

Change-Id: Idf5badabf0f79c0c513113c95a730c26d14ae083
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>