perf(db): use Into to encode StoredNibbles (#11350)

crates/storage/db-api/src/models/mod.rs

@@ -125,9 +125,9 @@ impl Encode for StoredNibbles {
 
     // Delegate to the Compact implementation
     fn encode(self) -> Self::Encoded {
-        let mut buf = Vec::with_capacity(self.0.len());
-        self.to_compact(&mut buf);
-        buf
+        // NOTE: This used to be `to_compact`, but all it does is append the bytes to the buffer,
+        // so we can just use the implementation of `Into<Vec<u8>>` to reuse the buffer.
+        self.0.into()
     }
 }