Cancel queries on timeout/connection close

[raghavan-arvind]

Hi!

We've been running into several issues where we run expensive queries in Metabase against Clickhouse. When these queries timeout, users tend to refresh the page to run them again, but we believe the original query is still running in Clickhouse. This leads to performance degradation for all users. Was wondering if we had considered supporting canceling queries on connection close/timeouts which would help prevent this.