Enhancement request: disable pg_stat_statements when running anything but validation

[itrofimow]

HI!

It can be seen in hardware stats of continuous runs (https://tfb-status.techempower.com/) that top-performing frameworks are actually bottlenecked by the database backend in some tests (namely, queries and updates): for example, ntex, which tops multiple queries test with impressive 34k RPS, is idle ~30-35% of the time (click 4 -> somewhere in the middle of the list -> total_cpu_usage).

Obviously pg_stat_statements is not the problem in itself, however it does consume some database resources, and freeing these resource could in turn help put a bit more load on the framework under measurement.

So what i propose is to disable pg_stat_statements PostgreSQL extension right after the framework passes validation (afaik the extension is only used in validation).