cluster spec sheet: OPTIMIZE TABLE after seeding the MySQL source table

The QA table now carries a PRIMARY KEY, and the seeding INSERT emits
customer_id in scattered order; inserted out of key order, the clustered
index page-splits to ~2.5x its packed size (11.5 GiB instead of 4.6 GiB
for 50M rows), which is what doubled the source_ingestion hydration
measurement from ~4m to ~8m after the July 24 re-seed. OPTIMIZE TABLE
rebuilds it packed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: peterdukelarsen

test/cluster-spec-sheet/mzcompose.py

@@ -2161,6 +2161,7 @@ def setup(self) -> list[str]:
         #         UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) h
         # ) nums
         # WHERE n BETWEEN 1 AND 50000000;
+        # OPTIMIZE TABLE tbl;
 
         # Kafka (Confluent)
         # node /usr/local/bin/datagen -f avro -n 50000000 -w 0 -p qa_cluster_spec_sheet -s table.json