fix(page_service): walredo logging problem (#6460)

Fixes: #6459 by formatting full causes of an error to log, while keeping
the top level string for end-user.

Changes user visible error detail from:

```
-DETAIL:  page server returned error: Read error: Failed to reconstruct a page image:
+DETAIL:  page server returned error: Read error
```

However on pageserver logs:

```
-ERROR page_service_conn_main{...}: error reading relation or page version: Read error: Failed to reconstruct a page image:
+ERROR page_service_conn_main{...}: error reading relation or page version: Read error: reconstruct a page image: launch walredo process: spawn process: Permission denied (os error 13)
```

pageserver/src/page_service.rs

@@ -322,8 +322,8 @@ enum PageStreamError {
     Shutdown,
 
     /// Something went wrong reading a page: this likely indicates a pageserver bug
-    #[error("Read error: {0}")]
-    Read(PageReconstructError),
+    #[error("Read error")]
+    Read(#[source] PageReconstructError),
 
     /// Ran out of time waiting for an LSN
     #[error("LSN timeout: {0}")]
@@ -332,11 +332,11 @@ enum PageStreamError {
     /// The entity required to serve the request (tenant or timeline) is not found,
     /// or is not found in a suitable state to serve a request.
     #[error("Not found: {0}")]
-    NotFound(std::borrow::Cow<'static, str>),
+    NotFound(Cow<'static, str>),
 
     /// Request asked for something that doesn't make sense, like an invalid LSN
     #[error("Bad request: {0}")]
-    BadRequest(std::borrow::Cow<'static, str>),
+    BadRequest(Cow<'static, str>),
 }
 
 impl From<PageReconstructError> for PageStreamError {
@@ -667,7 +667,10 @@ impl PageServerHandler {
                         // print the all details to the log with {:#}, but for the client the
                         // error message is enough.  Do not log if shutting down, as the anyhow::Error
                         // here includes cancellation which is not an error.
-                        span.in_scope(|| error!("error reading relation or page version: {:#}", e));
+                        let full = utils::error::report_compact_sources(&e);
+                        span.in_scope(|| {
+                            error!("error reading relation or page version: {full:#}")
+                        });
                         PagestreamBeMessage::Error(PagestreamErrorResponse {
                             message: e.to_string(),
                         })

pageserver/src/tenant/timeline.rs

@@ -4388,7 +4388,7 @@ impl Timeline {
                     .walredo_mgr
                     .request_redo(key, request_lsn, data.img, data.records, self.pg_version)
                     .await
-                    .context("Failed to reconstruct a page image:")
+                    .context("reconstruct a page image")
                 {
                     Ok(img) => img,
                     Err(e) => return Err(PageReconstructError::WalRedo(e)),