Remove mentions of in preview (#1938)

Fixes #1934 and removes in preview mentions for Azure and GCP Serverless
(in the [Core platform
capabilities](https://www.elastic.co/docs/deploy-manage/deploy/elastic-cloud/differences-from-other-elasticsearch-offerings#core-platform-capabilities)
table), which are now GA for Serverless regions.

Author: yetanothertw

deploy-manage/deploy/elastic-cloud/differences-from-other-elasticsearch-offerings.md

@@ -58,7 +58,7 @@ This table compares the core platform capabilities between {{ech}} deployments a
 | **Audit logging** | ✅ | **Planned** | Anticipated in a future release |
 | **Authentication realms** | ✅ | ✅ | Managed at organization level in Serverless; deployment level in Hosted |
 | **BYO-Key for Encryption at Rest** | ✅ | **Planned** | Anticipated in a future release; data in Serverless is stored on cloud-provider encrypted object storage |
-| **Cloud provider support** | - AWS <br>- GCP <br>- Azure | - AWS <br>- Azure (in preview) <br>- GCP (in preview) | - [{{ech}} regions](cloud://reference/cloud-hosted/regions.md)<br>- [Serverless regions](/deploy-manage/deploy/elastic-cloud/regions.md) |
+| **Cloud provider support** | - AWS <br>- GCP <br>- Azure | - AWS <br>- Azure <br>- GCP | - [{{ech}} regions](cloud://reference/cloud-hosted/regions.md)<br>- [Serverless regions](/deploy-manage/deploy/elastic-cloud/regions.md) |
 | **Cluster scaling** | Manual with autoscaling option | Managed | Automatic scaling eliminates capacity planning - [Learn more](https://www.elastic.co/blog/elastic-serverless-architecture) |
 | **Custom plugins and bundles** | ✅ | ❌ | Not available in Serverless |
 | **Custom roles** | ✅ | ✅ | Not available in Serverless Observability projects. |