Default timeout for queries

[sarahzinger]

Discussed in https://github.com/grafana/timestream-datasource/discussions/232

^{Originally posted by guelfey April 24, 2023}
Hi, we're successfully using this data source to visualize some internal metrics to our developers. We want them to be able to freely explore the data and create their own dashboards as they find useful. At the same time, it's possible that someone accidentally runs a query where some filter is missing that then causes a large amount of data to be scanned, and specifically for Timestream this then directly translates to a large cost. One idea to limit this would be to have a default timeout in the DataSource for all queries to Timestream, similar to how it's already possible to configure this for the CloudWatch or Prometheus data sources. This way, it's possible to prevent queries from running too long in a central place. Does that sound reasonable? I'd be happy to provide a PR in this case.