Parameterize mev-boost image override ability in the Holesky sample configs

[boulder225]

🎯 Problem to be solved

We need to parameterize the mev-boost image override ability in the Holesky sample configs to test it on the mainnet.

🛠️ Proposed solution

• Identify the existing Holesky sample configs that need to be modified
• Determine the best approach to parameterize the mev-boost image override (e.g., environment variables, configuration files)
• Implement the necessary changes to the Holesky sample configs to allow parameterization of the mev-boost image
• Document the process for overriding the mev-boost image in the sample configs

[boulder225]

Hey team! Please add your planning poker estimate with Zenhub @gsora @KaloyanTanev @pinebit

[gsora]

This is being worked on as we speak: ObolNetwork#64