fix(preview-environments): Adapt to C8 Helm chart v11

[maxdanilov]

Description

fix(preview-environments): Adapt to C8 Helm chart v11

The preview environments code has recently been upgraded to use Helm charts v11 (#3476), but no corresponding follow-up adjustments have been done to the code to conform to it (breaking changes in v10, v11)

• The separate Camunda-developed Identity subchart is not existent since v10 and has been integrated natively into the chart
• identity.keycloak became identityKeycloak (ref)
• elasticsearch.host is now elasticsearch.url.host
• zeebe-gateway became zeebeGateway

Related issues

Related: https://camunda.slack.com/archives/C5AHF1D8T/p1728980290646239

closes #

Checklist

• PR has a milestone or the no milestone label.

[maxdanilov]

This is WIP, not to be reviewed yet.

[github-actions]

🚀 Deployment Results 🚀

Please find below the results of the latest deployments.

connectors-preview-enrivon-c8sm

• Status: ✅
• URL: 🌐 Link
• ArgoCD: 🔗 Link
• Deployment Jobs: 📋 Link

🔧 Troubleshooting 🔧

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In case of error, please check 📋 Deployment Jobs and 🔗 ArgoCD to debug, and check our (yet to come) troubleshooting page