Issue Description: 

We have different approaches to managing secrets across our various environments. For example:

• local dev - Environment file
• dev/stable - We use Sealed Secrets
• stage - Hashicorp vault
• CVP pipeline tests: Originally Jenkins secrets, but potentially Sealed Secrets
• Perf testing: Attempting to work with Sealed Secrets.

For a small team, this range of approaches is not sustainable. In addition it is already posing numerous challenges in keeping secrets consistent across all environments.

In addition, other teams trying to work with RHOSE are finding it hard to understand and apply our approaches to Secret management.

Acceptance Criteria: 

• Define and document a consistent approach to secret management
• Ensure that it can be applied in any environment

Additional Information: 

• Our app-interface deployment of the Fleet Manager uses Hashicorp Vault for secret management. We should consider if we can adopt this technology for all environments.