Add metrics for CI/CD Catalog publishing allowlist feature

Summary

Implement metrics to track usage and effectiveness of the CI/CD Catalog publishing allowlist feature (application setting ci_cd_catalog_projects_allowlist).

Metrics to Implement

As mentioned in #582044 (closed), the following metrics should be tracked:

1. Number of unique instances using this feature

   • Tracks: How many self-managed/Dedicated instances have configured the allowlist

2. Number of components blocked by this setting

   • Tracks: How many component publication attempts were rejected due to allowlist restrictions
   • Event: Triggered when Ci::Catalog::Resources::ReleaseService rejects a publish attempt due to allowlist validation

Implementation Details

• Follow GitLab internal analytics documentation
• Metrics should be collected for Self-Managed/Dedicated instances
• Ensure metrics respect privacy and don't expose sensitive project information

Related Issues

• Parent feature: #582044 (closed)
• Related epic: &14060 (closed)