[BUG] PullLog Operator should update the next pull offset to be the l…

…ast record offset + 1 of previous pull (#2056)

## Description of changes

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
- The PullLogOperator does not correctly update the offset after the
first fetch as it might return less records than the batch size.
 - New functionality
	 - ...

## Test plan
*How are these changes tested?*

- [ ] Tests pass locally with `pytest` for python, `yarn test` for js,
`cargo test` for rust

## Documentation Changes
*Are all docstrings for user-facing APIs updated if required? Do we need
to make documentation changes in the [docs
repository](https://github.com/chroma-core/docs)?*

rust/worker/src/execution/operators/pull_log.rs

@@ -117,7 +117,8 @@ impl Operator<PullLogsInput, PullLogsOutput> for PullLogsOperator {
             }
 
             num_records_read += logs.len();
-            offset += batch_size as i64;
+            // unwrap here is safe because we just checked if empty
+            offset = logs.last().unwrap().log_offset + 1;
             result.append(&mut logs);
 
             // We used a a timestamp and we didn't get a full batch, so we have retrieved