Clarify the 1 second requirement is for a cold database_lab run

doc/development/telemetry/usage_ping.md

@@ -299,7 +299,7 @@ Paste the SQL query into `#database-lab` to see how the query performs at scale.
 
 - `#database-lab` is a Slack channel which uses a production-sized environment to test your queries.
 - GitLab.com’s production database has a 15 second timeout.
-- For each query we require an execution time of under 1 second due to cold caches which can 10x this time.
+- Any single query must stay below 1 second execution time with cold caches.
 - Add a specialized index on columns involved to reduce the execution time.
 
 In order to have an understanding of the query's execution we add in the MR description the following information: