Refacto/eosu 1007 replace eos config tests with product config-->6.1.0

[OswaldoApexSystems]

EOSU 1007 Update Config/EOSConfigTests.cs

This change migrates the configuration system from the legacy EOSConfig
model to the new ProductConfig-based architecture.

Key points of this migration:

• Replaced EOSConfig usage with ProductConfig as the main configuration
  entry point across runtime and tests.
• Refactored validation logic to rely on strong typing and domain
  invariants instead of string parsing.
• Introduced dedicated FieldValidators aligned with the new model:
  • GUIDFieldValidatorAttribute for Guid-based fields (rejects Guid.Empty).
  • SandboxIdFieldValidatorAttribute for SandboxId value object validation.
  • ProductionEnvironmentsFieldValidatorAttribute to validate deployment
    aggregates.
  • ClientCredentialsFieldValidatorAttribute to ensure at least one
    complete client credential exists.
• Removed legacy string-based ID validation patterns in favor of
  semantic validation using Guid, SandboxId, and aggregate state.

Domain model improvements:

• Deployment validity is now expressed exclusively through domain
  invariants (Deployment.IsComplete) instead of FieldValidator usage.
• SandboxId was hardened to be null-safe and robust against invalid input,
  preventing runtime exceptions and clarifying the distinction between
  "valid", "invalid", and "empty" states.
• Validation responsibilities are now clearly split:
  • FieldValidators validate configuration completeness at the
    ProductConfig boundary.
  • Domain objects (Deployment, SandboxId, Credentials) enforce their
    own invariants internally.

Test suite updates:

• Removed or migrated EOSConfig tests to ProductConfigTests.
• Added comprehensive test coverage for:
  • ProductConfig fields and validators.
  • ProductionEnvironments and ClientCredentials aggregates.
  • Deployment domain invariants.
  • SandboxId value object behavior, including edge cases, rollback
    behavior, and format semantics.
• Ensured tests are deterministic by explicitly resetting singleton
  config state between test cases.

Overall, this commit modernizes the configuration system by:

• Eliminating legacy parsing-based validation.
• Making invalid states unrepresentable through strong typing.
• Aligning runtime behavior, validation, and tests around the same
  domain rules.