[Docs] Update self-hosted deployment instructions with new

[pontusringblom]

Current State

This page needs updated: https://docs.layer5.io/cloud/self-hosted/deployment/.

Maybe a new page needs to be added to the planning guide - https://docs.layer5.io/cloud/self-hosted/planning/

Desired State

Incorporate user-facing documentation about the purpose and use of the INIT_CONFIG environment variable. References:

• https://github.com/layer5io/meshery-cloud/pull/4652#issue-3731818019
• https://github.com/layer5io/meshery-cloud/blob/e055f067706e7c376dc77e03d224af90a0cfb2d6/docs/provider-init.md

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