Add option from datakey to be provided from existing secret

[dan-transmit]

Desired Outcome

The secret doesn't show in the helm values

Implemented Changes

Allow to use existing secrets in the cluster

Connected Issue/Story

Resolves #[relevant GitHub issue(s), e.g. 76]

CyberArk internal issue ID: [insert issue ID]

Definition of Done

At least 1 todo must be completed in the sections below for the PR to be merged.

Changelog

• [x] The CHANGELOG has been updated, or
• [ ] This PR does not include user-facing changes and doesn't require a CHANGELOG update

Test coverage

• [ ] This PR includes new unit and integration tests to go with the code changes, or
• [x] The changes in this PR do not require tests

Documentation

• [x] Docs (e.g. READMEs) were updated in this PR
• [ ] A follow-up issue to update official docs has been filed here: [insert issue ID]
• [ ] This PR does not require updating any documentation

Behavior

• [ ] This PR changes product behavior and has been reviewed by a PO, or
• [ ] These changes are part of a larger initiative that will be reviewed later, or
• [x] No behavior was changed with this PR

Security

• [ ] Security architect has reviewed the changes in this PR,
• [ ] These changes are part of a larger initiative with a separate security review, or
• [ ] There are no security aspects to these changes

[dan-transmit]

Writing a test would mean to create a whole new setup (it's not like the current script has a reusable interface). If you think that dataKeySecretRef should be the preferred usage, then I can replace dataKey from the tests with it.

[szh]

That's true. Ideally we'd refactor the tests to make it easier to have multiple test cases. If this isn't something you're interested in doing I totally understand, we just can't merge it without tests. I'm fine to put this on hold for a bit until we can do that internally if that's ok with you.