Sampler: Query timeout is not configurable

[altmannmarcelo]

Description

At the moment, we abort a query if it takes more than 1 second. When we do it, we end up producing a warning which might flood the log:

2025-12-01T09:20:36.654914Z  WARN readyset_adapter::sampler: Sampler upstream read timeout
2025-11-27T10:31:21.644407Z  WARN readyset_adapter::sampler: Sampler upstream read timeout
2025-11-27T06:43:12.226307Z  WARN readyset_adapter::sampler: Sampler upstream read timeout

We should make the timeout a configuration.

Change in user-visible behavior

Requires documentation change