This commit makes the error message and log entry that appear when one
tries to create a bridge with a name the exceeds 255 bytes (the max
length for atoms) more friendly and easier to understand.
An even better fix would be to not store bridge names as atoms but this
probably requires a more substantial change.
Fixes:
https://emqx.atlassian.net/browse/EMQX-9609
```
%%% emqx_channel_SUITE ==> t_handle_kicked_publish_will_msg: FAILED
%%% emqx_channel_SUITE ==> will_message_not_published
```
The problem was that the whole generated message was compared for
equality when receiving the will message, but the timestamp may be
different at publishing time...