fix(pageserver): do not log no-route-to-host errors (#12468)

## Problem

close https://github.com/neondatabase/neon/issues/12344

## Summary of changes

Add `HostUnreachable` and `NetworkUnreachable` to expected I/O error.
This was new in Rust 1.83.

Signed-off-by: Alex Chi Z <chi@neon.tech>

libs/postgres_backend/src/lib.rs

@@ -78,7 +78,13 @@ pub fn is_expected_io_error(e: &io::Error) -> bool {
     use io::ErrorKind::*;
     matches!(
         e.kind(),
-        BrokenPipe | ConnectionRefused | ConnectionAborted | ConnectionReset | TimedOut
+        HostUnreachable
+            | NetworkUnreachable
+            | BrokenPipe
+            | ConnectionRefused
+            | ConnectionAborted
+            | ConnectionReset
+            | TimedOut,
     )
 }