AcctIdx: fix infinite loop (#23806) (#23816)

(cherry picked from commit 965ab9186d)

Co-authored-by: Jeff Washington (jwash) <wash678@gmail.com>

runtime/src/in_mem_accounts_index.rs

@@ -1027,6 +1027,7 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
                             Ok(_) => {
                                 // successfully written to disk
                                 flush_entries_updated_on_disk += 1;
+                                break;
                             }
                             Err(err) => {
                                 // disk needs to resize. This item did not get resized. Resize and try again.