Radar: multitabs for GCP and AWS auth

[kaitlynmichael]

Note

Low Risk
Documentation-only updates to connection guidance with no application or security logic changes.

Overview
Splits ElastiCache and Google Memorystore connection docs by deployment model using multitabs so readers choose Radar on Redis Cloud vs Self-managed Radar.

For Amazon ElastiCache, the Redis Cloud tab documents cross-account IAM role assumption (account ID, Radar-generated external ID, role ARN, trust policy) instead of access keys; the self-managed tab keeps the existing long-lived key workflow.

For Google Memorystore, the Redis Cloud tab documents service account impersonation (tenant project label, roles/browser, granting Radar Service Account Token Creator, connection fields without a JSON key); the self-managed tab still describes pasting a service account key.

Shared prerequisites (IAM permissions, roles table, outbound HTTPS requirements) are unchanged and sit outside the tabs.

^{Reviewed by Cursor Bugbot for commit cfef79a. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

DOC-7076

[github-actions]

🧠 Redis Memory

Found 5 related items from repository history (5 new this commit):

• PR — Radar: add gRPC hostname 🆕
• Commit — Radar: add gRPC hostname 🆕

  Radar: add gRPC hostname

• PR — Radar: connect with agents 🆕

• PR — Radar agents file 🆕

• Commit — more screenshots 🆕

  more screenshots

Memory updated at cfef79a

[github-actions]

Staging links:
https://redis.io/docs/staging/DOC-7076/operate/radar/connect/