Fix https://github.com/chatmail/core/issues/7835.
The problem was most probably:
- `ac1_clone` receives the sync message, sends `TRANSPORTS_MODIFIED`
event, and launches a task that will restart IO
- After IO was stopped, but before it is started again,
`ac1_clone.add_transport_from_qr(qr)` is called
- this check fails:
```rust
ensure!(
!self.scheduler.is_running().await,
"cannot configure, already running"
);
```
This fixes the bug when a new transport doesn't become primary on the 2nd device because INBOX from
the new transport isn't fully fetched. Now the `Transports` sync message is received from the old
transport, but as it has updated "From", it updates the primary transport correspondingly. NB: I/O
for the new primary transport isn't immediately started however, this needs a separate fix.
Fix get_secondary_addrs() which was using
`secondary_addrs` config that is not updated anymore.
Instead of using `secondary_addrs` config,
use the `transports` table which contains all the addresses.
