fix[venom]: remove liveness requests

[harkal]

What I did

Sanitisation of liveness requests and invalidations

How I did it

How to verify it

Commit message

This commit sanitizes the requests/invalidations of liveness analysis in
the various passes. 

Additionally it renames the property `in_vars` to `liveness_in_vars` to
make it clear that this property is liveness dependent 

Description for the changelog

Cute Animal Picture

[charles-cooper]

lgtm, thanks!