[web] Don't render ThreadListProvider in CommunityDrawer

Summary:
Searched the codebase and couldn't find any use of ThreadListContext within this component tree. It was initially introduced in D6162, but I couldn't find any uses in that stack either.

This is an expensive component to render, so we should avoid rendering it unless necessary.

Test Plan:

1. I did a thorough search for all consumers of ThreadListContext and confirmed that there were none in this component tree.
2. I tested the web app in my local environment and didn't see any issues.
3. I tested the web app in a production setting (my personal server at comm.domains, pointed at my production keyserver on AWS) and didn't see any issues.

Reviewers: tomek

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D14021