This PR switches collab over to start minting access tokens using the
new OAEP-based encryption format.

This is a follow-up to #15058 where we added support for this new
encryption format.

Clients that are newer than 8 months ago should be able to decrypt the
new access tokens. It is only clients older than 8 months ago that will
no longer be supported.

Release Notes:

- N/A