[web] Fix creating subchannels in chats in GENESIS

Summary:
issue: ENG-8710
chats in GENESIS cannot be looking at the list of GENEISS members because every member sees just themselves in GENESIS

Test Plan:
tested that it is possible to create a subchannel to a chat in GENESIS
Tested that we see the same list of users as on native both when there is no search text, and when there is some search text

Reviewers: ashoat, tomek, ginsu

Reviewed By: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12667