[HOTFIX] applying PR #3431 to release/2025-01-03 (#3434)

This PR cherry-picks the commit 75aeb81
onto release/2025-01-03. If there are unresolved conflicts, please
resolve them manually.

Co-authored-by: Evan Culver <eculver@users.noreply.github.com>

rust/worker/src/segment/distributed_hnsw_segment.rs

@@ -213,7 +213,7 @@ impl SegmentWriter for DistributedHNSWSegmentWriter {
                     let embedding = record.merged_embeddings_ref();
 
                     let mut index = self.index.inner.upgradable_read();
-                    let index_len = index.len();
+                    let index_len = index.len_with_deleted();
                     let index_capacity = index.capacity();
                     if index_len + 1 > index_capacity {
                         index.with_upgraded(|index| {