Fix cascaded deletion of shared_access for users and rooms (#3055)

* GIT-2444: add test for deletion of shared rooms

* GIT-3054: add test for deletion of user with shared rooms

* GIT-2444: fix deletion of shared rooms

Fixes #2444

* GIT-3054: fix deletion of user with shared rooms

Fixes #3054

Co-authored-by: Ahmad Farhat <ahmad.af.farhat@gmail.com>