Schedule image layer uploads in tiered compaction (#7282)

Tiered compaction hasn't scheduled the upload of image layers. In the
`test_gc_feedback.py` test this has caused warnings like with tiered
compaction:

```
INFO request[...] Deleting layer [...] not found in latest_files list, never uploaded?
```

Which caused errors like:

```
ERROR layer_delete[...] was unlinked but was not dangling
```

Fixes #7244

pageserver/src/tenant/timeline.rs

@@ -3896,6 +3896,24 @@ impl Timeline {
         Ok(())
     }
 
+    /// Schedules the uploads of the given image layers
+    fn upload_new_image_layers(
+        self: &Arc<Self>,
+        new_images: impl IntoIterator<Item = ResidentLayer>,
+    ) -> anyhow::Result<()> {
+        let Some(remote_client) = &self.remote_client else {
+            return Ok(());
+        };
+        for layer in new_images {
+            remote_client.schedule_layer_file_upload(layer)?;
+        }
+        // should any new image layer been created, not uploading index_part will
+        // result in a mismatch between remote_physical_size and layermap calculated
+        // size, which will fail some tests, but should not be an issue otherwise.
+        remote_client.schedule_index_upload_for_file_changes()?;
+        Ok(())
+    }
+
     /// Update information about which layer files need to be retained on
     /// garbage collection. This is separate from actually performing the GC,
     /// and is updated more frequently, so that compaction can remove obsolete

pageserver/src/tenant/timeline/compaction.rs

@@ -125,18 +125,8 @@ impl Timeline {
                     )
                     .await
                     .map_err(anyhow::Error::from)?;
-                if let Some(remote_client) = &self.remote_client {
-                    for layer in layers {
-                        remote_client.schedule_layer_file_upload(layer)?;
-                    }
-                }
 
-                if let Some(remote_client) = &self.remote_client {
-                    // should any new image layer been created, not uploading index_part will
-                    // result in a mismatch between remote_physical_size and layermap calculated
-                    // size, which will fail some tests, but should not be an issue otherwise.
-                    remote_client.schedule_index_upload_for_file_changes()?;
-                }
+                self.upload_new_image_layers(layers)?;
             }
             Err(err) => {
                 // no partitioning? This is normal, if the timeline was just created
@@ -818,7 +808,10 @@ impl TimelineAdaptor {
         self.timeline
             .finish_compact_batch(&self.new_deltas, &self.new_images, &layers_to_delete)
             .await?;
-        self.new_images.clear();
+
+        self.timeline
+            .upload_new_image_layers(std::mem::take(&mut self.new_images))?;
+
         self.new_deltas.clear();
         self.layers_to_delete.clear();
         Ok(())