Fixes for scaling proxy and native charm

With changes in here, it can remove application while scaling in
and it can add application existed k8s proxy charm model.

Change-Id: If4fd378fdafd925fa1750ce4769506b44adc233c
Signed-off-by: aktas <emin.aktas@ulakhaberlesme.com.tr>
(cherry picked from commit d1d5541e)