chainio: use package logger instead of instance logger

There's no guarantee that the `b.beat` is initialized when the
dispatcher shuts down, especially with the case in the remote signer
where no chainbackend is created.

docs/release-notes/release-notes-0.19.2.md

@@ -26,6 +26,9 @@
 - [Fixed](https://github.com/lightningnetwork/lnd/pull/9921) a case where the
   spending notification of an output may be missed if wrong height hint is used.
 
+- [Fixed](https://github.com/lightningnetwork/lnd/pull/9962) a case where the
+  node may panic if it's running in the remote signer mode.
+
 # New Features
 
 ## Functional Enhancements