set staging docker registry for staging clusters

[anish-mudaraddi]

Description:

allows us to test changes to docker registry

Special Notes:

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Submitter:

Have you:

• Labelled this PR, e.g. bug, deployment, enhancement ...etc.

• A deployment can be reviewed, and merged, by a single reviewer.
• It can only be used to deploy, change, or remove clusters based on existing patterns for staging.
• Anything involving prod, or production facing services must use the normal 2 person review.
• All other PR types require the usual PR process (e.g. 2 person).

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Reviewer

Have you:

• Verified this PR uses the correct label(s) based on the rules above?
• Checked if this could affect production (e.g. a global value that's changed without an override)?
• Tested setting this up, if it's not a deployment, to verify it can be redeployed with any documentation if appropriate?