UTD Hook | UTD will never be reported if the timeline controller is dropped before the `max_delay`

When a UTD is reported, the hook manager will spawn a task to be executed after `max_delay`:

https://github.com/matrix-org/matrix-rust-sdk/blob/9b6de4e4367a465b7605eb931d0e4375df8f5ddd/crates/matrix-sdk-ui/src/unable_to_decrypt_hook.rs#L233-L236

However, if the hook is dropped before the expiration of this timer the UTD will never be reported:

https://github.com/matrix-org/matrix-rust-sdk/blob/9b6de4e4367a465b7605eb931d0e4375df8f5ddd/crates/matrix-sdk-ui/src/unable_to_decrypt_hook.rs#L315-L318

The current default for that delay is 60s. This particularly affects clients like EXI that don't keep timelines around; EXA has a LRU cache of the last 16 opened timelines.

Some notes:
- We would want to keep the reporting task around (surviving the hook lifetime), but then we might not detect late decryption anymore because this is done by the timeline controller
- Maybe we should move that code to the event cache
- As a stop gap we could reduce the max delay to around 10s? would reduce the chances of having it dropped

Start in crates/matrix-sdk-ui/src/unable_to_decrypt_hook.rs at the timer creation and timeline-controller drop handling linked in the issue. Trace how the reporting task and late decryption depend on the hook lifetime, then resolve which lifecycle location should own the task; done means UTD reports still occur when the timeline controller is dropped before max_delay.

Written by the indexing model from the issue text.