cleanups to make CI pass (well, fail because the bug isn't fixed yet)

pageserver/src/bin/test_helper_slow_client_reads.rs

@@ -50,7 +50,8 @@ async fn main() -> anyhow::Result<()> {
         let _: () = res?;
     }
 
-    stdout().write(b"R")?;
+    let n = stdout().write(b"R")?;
+    assert_eq!(n, 1);
     stdout().flush()?;
 
     eprintln!("waiting for signal to tell us to exit");

pageserver/src/page_service.rs

@@ -617,6 +617,7 @@ impl BatchedFeMessage {
                     page.timer.observe_execution_start(at);
                 }
             }
+            #[cfg(feature = "testing")]
             BatchedFeMessage::Test { requests, .. } => {
                 for req in requests {
                     req.timer.observe_execution_start(at);
@@ -960,6 +961,7 @@ impl PageServerHandler {
                 accum_pages.extend(this_pages);
                 Ok(())
             }
+            #[cfg(feature = "testing")]
             (
                 Ok(BatchedFeMessage::Test {
                     shard: accum_shard,
@@ -1885,7 +1887,7 @@ impl PageServerHandler {
 
             results.push({
                 if timeline.cancel.is_cancelled() {
-                    Err(PageStreamError::Shutdown)
+                    Err(PageReconstructError::Cancelled)
                 } else {
                     Ok(())
                 }