[Utility] Adjust default configuration based on the user-defined configuration

[adshmh]

Objective

Default configuration should not result in errors. More specifically, there seems to be some scenarios where user-defined configuration should result in a modified default configuration. For example, currently if the user enables fisherman, the default servicer configuration will still be applied, resulting in an error when initializing the utility module, because fisherman and servicer cannot both be enabled.

Origin Document

Encountered this in #803, after adding a default servicer configuration.

and the corresponding set of unit tests that would fail if a servicer default config is added:

Goals

• The default configuration should take into account the user-defined configuration, see the above description for an example.

Deliverable

• Updated Code to implement the required adjustments: involves using viper differently (or changing to a different config library)
• Updated README/documentation to list all invalid combinations along with the corresponding reasons.
• Allow the default servicer config to be applied when there are no contradictions with the user-defined configuration.

Non-goals / Non-deliverables

General issue deliverables

• Update any relevant local/global README(s)
• Update relevant source code tree explanations
• Add or update any relevant or supporting mermaid diagrams

Testing Methodology

• Task specific tests or benchmarks: make ...
• New tests or benchmarks: make ...
• All tests: make test_all
• LocalNet: verify a LocalNet is still functioning correctly by following the instructions at docs/development/README.md
• k8s LocalNet: verify a k8s LocalNet is still functioning correctly by following the instructions here

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Creator: [@adshmh]
Co-Owners: [@Olshansk]