Move create snapshot to finally block

In case if create diagnostic snapshot failed,
we can not create env snapshot with devops.
To avoid this  - move create snapshot in finally block

Change-Id: I6826930d997006a51ca79b94314f7df3c06b2f66
Closes-Bug: #1325907
(cherry picked from commit c021106c9b61e34bc24ad464b42a6104ce66bb7a)