Update Opensearch port requirements

What does this MR do?

The current documentation around port requirement only mentions port 9200 which is usually the case for Elasticsearch. However if OpenSearch is used instead, using port 9200 can break the page as the Opensearch Service only supports port 80 and 443.

OpenSearch Service only accepts connections over port 80 (HTTP) or 443 (HTTPS).

If users unexpectedly use port 9200 initially, they can't change it in the UI anymore as the page will render 500 response. They will have to workaround this by updating the port using the rails console.

Related issues

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