Fix: index events according to their local row id (#4762)

We use this row id as a watermark, and update it after every ingestion
of an event. Previously, we were iterating over things in an undefined
order, and effectively sometimes ingesting events out of order, causing
bad things to happen to the watermark, leading to much FUN.

## Checklist before requesting a review

- [x] If this code contains consensus-breaking changes, I have added the
"consensus-breaking" label. Otherwise, I declare my belief that there
are not consensus-breaking changes, for the following reason:

  > indexing

crates/util/cometindex/src/indexer.rs

@@ -239,6 +239,8 @@ GROUP BY
     events.type, 
     blocks.height, 
     tx_results.tx_hash
+ORDER BY
+    events.rowid ASC
         "#,
     )
     .bind(watermark)