[Serverless] Remove (in preview) for Azure and GCP Serverless regions

[KOTungseth]

Type of issue

Inaccurate

What documentation page is affected

https://www.elastic.co/docs/deploy-manage/deploy/elastic-cloud/differences-from-other-elasticsearch-offerings

What happened?

Azure and GCP are now GA for Serverless regions. We can remove (in preview).

Additional info

No response