[web] Hide members option in ThreadMenu for all private and personal threads

Summary:
We currently only hide this menu option for threadTypes.GENESIS_PERSONAL. I think we should match behavior for threadTypes.PERSONAL, and I also figure we can hide the menu option for private threads too (threadTypes.PRIVATE and threadTypes.GENESIS_PRIVATE, which are for a user chatting with themselves).

Depends on D13549

Test Plan: Confirm that members options doesn't appear in ThreadMenu on web when viewing a PRIVATE thread

Reviewers: tomek, kamil, inka

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D13550