LU-17075 osd: destroy declare shouldn't panic

LU-17075 osd: destroy declare shouldn't panic

if the object doesn't exist during declaration.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I7d42cad0c04e7941a2f7950fdddaf7c473998b12
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/52496
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>