[lib] Avoid unnecessary state change in user reducer

Summary: We don't want to introdue state change if it didn't really change. This will avoid unneccesaryy rerenders

Test Plan: Tested that if filteredUserIDs.length === 0 the returcer returns unchanged state

Reviewers: tomek, kamil

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12328