History sharing doesn't work if the key bundle message arrives after the join #30740
Description
With the history sharing feature enabled, when Alice invites Bob to a room, she will also send him a to-device message containing details of the encryption keys.
If that to-device message is sufficiently delayed that Bob accepts the invite before it arrives, he will never download the key bundle and will therefore see only UTDs.
matrix-org/matrix-rust-sdk#5322 fixed this for Element X, but we forgot Element Web.