poetry: remove fabric and netns dependencies

With the ControlMaster/ControlPersist approach, these are no needed
anymore. I'm not reverting the commit that added them because that also
contained an update of poetry.lock. I'm also not rebuilding the devctr
for this because the dependencies will simply be dropped the next time
we're rebuilding it.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat