Migrate isApiInfoJsonSchema to use built-in schema function

[andreyyudin]

Description:
Refactor src/functions/isApiInfoJsonSchema.js to use Spectral’s built-in schema function instead of a custom validation implementation. This will align the rule with the current best practices for schema-based validation in Spectral and reduce maintenance overhead.

Benefits:

• Leverages Spectral’s native schema handling and validation capabilities.
• Simplifies codebase by removing custom JSON schema logic.
• Ensures consistent validation behavior across all rules.

Acceptance Criteria:

• isApiInfoJsonSchema.js no longer exists.
• The rule calls Spectral’s built-in schema function for evaluation.
• Unit tests confirm equivalent or improved behavior compared to the old implementation.

Proposed Steps:

1. Replace custom validation logic with Spectral schema function usage.
2. Update rule configuration and references accordingly.
3. Verify rule output consistency with tests.