fix(tests): deflake test_wal_and_sst_storage_overhead against vanished files

grovedb/src/tests/test_compaction_sizes.rs

@@ -21,7 +21,17 @@ mod tests {
             .expect("cannot read dir")
             .filter_map(|entry| entry.ok())
             .filter(|entry| entry.path().extension().is_some_and(|ext| ext == extension))
-            .map(|entry| entry.metadata().unwrap().len())
+            // Background compaction can delete a file between the read_dir
+            // listing and the metadata() call; skip vanished files.
+            .filter_map(|entry| match entry.metadata() {
+                Ok(metadata) => Some(metadata),
+                Err(error) if error.kind() == std::io::ErrorKind::NotFound => None,
+                Err(error) => panic!(
+                    "cannot read metadata for {}: {error}",
+                    entry.path().display()
+                ),
+            })
+            .map(|metadata| metadata.len())
             .sum()
     }