"Protecting media from quarantine" terminology is confusing

This issue has been migrated from [#13462](https://github.com/matrix-org/synapse/issues/13462).

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Today, using the Admin API, homeserver admins can both:

* ["quarantine" media](https://matrix-org.github.io/synapse/latest/admin_api/media_admin_api.html#quarantine-media), which will hide that media from users but keep it on the homeserver, and
* ["protect" media](https://matrix-org.github.io/synapse/latest/admin_api/media_admin_api.html#protecting-media-from-being-quarantined), which prevents a piece of media from being quarantined. This is mostly used to protect known sticker packs when all media in a room is quarantined.

Additionally, [media retention](https://matrix-org.github.io/synapse/latest/usage/configuration/config_documentation.html#media_retention) will not delete "quarantined" media - irregardless of its "protection" bit.

The "protect" terminology is a bit confusing. I feel like "protecting" media would prevent it from being deleted typically, where in our case it's "protection from quarantine".

This question came up on the subject of "protecting" rooms from automatic purging (when all users leave and forget a room). Perhaps instead of "protected media", we should say something along the lines of "whitelisted" or "verified" media.