[lib] Add COMMUNITY_ROOT to getThreadTypeParentRequirement as disabled
[lib] Add COMMUNITY_ROOT to getThreadTypeParentRequirement as disabled

Summary: This is just for completeness. It should never be a problem, since it's currently only possible for `COMMUNITY_ROOT`s to be created programmatically (in other words, they're not creatable via the API).

Test Plan: Nothing to test, this is just for completeness

Reviewers: atul

Reviewed By: atul

Subscribers: KatPo, palys-swm, Adrian

Differential Revision: https://phabricator.ashoat.com/D1280

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