Remove deprecated 'deactivate_image' feature flag setting

'deactivate_image' feature flag was added long back during kilo
cycle. Tempest is going to remove this feature flag.

Depends-On: I843d4c64f24407d9d217005d5ea59d50d7ad62e7
Change-Id: I1ae8efc0e62acc5e05c1c00dc8970b74d8b16da0
1 file changed