pageserver: mention key in walredo errors (#6988)

## Problem

- Walredo errors, e.g. during image creation, mention the LSN affected
but not the key.

## Summary of changes

- Add key to "error applying ... WAL records" log message

pageserver/src/walredo.rs

@@ -262,7 +262,7 @@ impl PostgresRedoManager {
             // next request will launch a new one.
             if let Err(e) = result.as_ref() {
                 error!(
-                    "error applying {} WAL records {}..{} ({} bytes) to base image with LSN {} to reconstruct page image at LSN {} n_attempts={}: {:?}",
+                    "error applying {} WAL records {}..{} ({} bytes) to key {key}, from base image with LSN {} to reconstruct page image at LSN {} n_attempts={}: {:?}",
                     records.len(),
                     records.first().map(|p| p.0).unwrap_or(Lsn(0)),
                     records.last().map(|p| p.0).unwrap_or(Lsn(0)),