[DOC] Add more to Best Practices Docs

[IanHoang]

Please provide details on how and where the documentation can be improved

https://docs.opensearch.org/docs/latest/benchmark/user-guide/optimizing-benchmarks/performance-testing-best-practices/

Could we add more details to the best practices here?

• Recommend using snapshots: the best way to get consistent reliable results is to swap out ingestion and use a snapshot. For example, if comparing two OpenSearch clusters with the same configurations but different OpenSearch versions, it'd useful to restore the same test workload snapshot onto both so that the shard toplogy and segment layout is identical. Keep in mind, this can only be done if the OpenSearch versions share the same underlying Lucene version. We sohuld add how to check this.

Provide references

No response

Additional context

No response