Add priorityClassName configuration to deployment

[LeonoreMangold]

What does this PR do?

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Developer Done List

• Tests Added/Updated
• Updated README.md
• Verified backward compatible
• Verified database migrations will not be catastrophic
• Considered Security, Availability and Confidentiality

For the Reviewer:

By approving this PR, the reviewer acknowledges that they have checked all items in this done list.

Reviewer/Approval Done List

• Tests Pass Locally
• CI Build Passes
• Verified README.md is updated
• Verified changes are backward compatible
• Reviewed impact to Security, Availability and Confidentiality (if issue found, add comments and request changes)

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[LeonoreMangold]

@daniel-spray @AnthonyApptio do you know to whom I can reach out for integration of this PR ? If possible, I would need it as soon as possible as part of an incoming feature in my team.
Much thanks !