Elasticsearch Client reference cleanup

[lcawl]

The reference information that was added to the Elasticsearch client repos (via 244, 762, 952, 1432, 2635, 2806, 8640) requires the following clean-up;

• Consolidate stateful and stack "Getting started" client pages e.g. https://docs-v3-preview.elastic.dev/elastic/elasticsearch-js/tree/main/reference/getting-started
• Broken codeblocks within tables e.g. https://docs-v3-preview.elastic.dev/elastic/elasticsearch-js/tree/main/reference/basic-config