Turn on Threads for all users (out of labs)

[novocaine]

Make the threads feature available for all users.

Depends on element-hq/element-meta#187

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We aim to release Threads on 20 December, we will do so by:

• completing testing before the RC and during the RC period (both team, internal, and community)
• defaulting the labs flag to on for users

Once released, we should remove the labs flag with at least one cycle between 20 December and the removal of the switch in product.

[janogarcia]

@novocaine After internal discussion, it was decided not to provide a user setting to disable threads (it’s not entirely replacing an existing feature, it can lead to degraded experience for everyone as conversations get split between the thread and main timeline, etc.).

[daniellekirkwood]

threads was available to all users by default on december 20 on iOS, closing this issue.