[BUG] Add check for empty memberlist for compactor scheduler (#1998)

## Description of changes

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
	 - This PR adds check for empty memberlist. 
 - 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/compactor/scheduler.rs

@@ -132,9 +132,9 @@ impl Scheduler {
     }
 
     pub(crate) async fn schedule(&mut self) {
-        if self.memberlist.is_none() {
+        if self.memberlist.is_none() || self.memberlist.as_ref().unwrap().is_empty() {
             // TODO: Log error
-            println!("Memberlist is not set");
+            println!("Memberlist is not set or empty. Cannot schedule compaction jobs.");
             return;
         }
         let collections = self.get_collections_with_new_data().await;
@@ -262,6 +262,13 @@ mod tests {
         let jobs = scheduler.get_jobs();
         assert_eq!(jobs.count(), 0);
 
+        // Set empty memberlist
+        // Scheduler does nothing with empty memberlist
+        scheduler.set_memberlist(vec![]);
+        scheduler.schedule().await;
+        let jobs = scheduler.get_jobs();
+        assert_eq!(jobs.count(), 0);
+
         // Set memberlist
         scheduler.set_memberlist(vec![my_ip.clone()]);
         scheduler.schedule().await;