Unable to remove deleted groups from project roles

Summary

Once you delete a group from the User Management, the groups aren't removed from the roles that they were added to and they still show up in People section for the project.
Once you attempt to remove the group from the role, it fails with the following error message:

Group 'x' was not found in the system.

Steps to Reproduce

1. Create a group
2. Add the newly created group to a Role in People section of a Project
3. Delete the group
4. Try to remove the group from the role previously added

Expected Results

1) Once you delete the group, the group should be removed automatically from all the roles that they're added to.
2) Remove the group from the role properly

Actual Results

The groups aren't automatically removed from the roles upon deletion of the groups, and it's not possible to remove them manually in the project roles.

Workaround

Recreate these groups using the exact same name, remove them from the project roles and then delete them from the User Management.