Fix Bug 2022: RO updating VIM details with null info when VM is in error state

This patch prevents to override the vim_details when VM
is in error state. By this way, vim_details could be used for healing operations.
The messages regarding with the failure is kept in another key names "vim_message".

Change-Id: Ie0b73040074865a89d9ab2d447e20a8f3d38d520
Signed-off-by: aticig <gulsum.atici@canonical.com>