Merge pull request #9496 from ellemouton/graph4

graph: remove redundant iteration through a node's persisted channels

docs/release-notes/release-notes-0.19.0.md

@@ -262,6 +262,11 @@ The underlying functionality between those two options remain the same.
 
 * Log rotation can now use ZSTD
 
+* [Remove redundant 
+  iteration](https://github.com/lightningnetwork/lnd/pull/9496) over a node's 
+  persisted channels when updating the graph cache with a new node or node 
+  update.
+
 ## Deprecations
 
 ### ⚠️ **Warning:** The following RPCs will be removed in release version **0.21**: