Remove VulnerabilityFindingDismiss GraphQL mutation

Why are we doing this work

This is the removal issue for the VulnerabilityFindingDismiss GraphQL mutation. It is being deprecated in %15.5 and scheduled for removal in %16.0.

Relevant links

• Deprecation Issue
• Deprecation MR

Non-functional requirements

• Documentation: Update GraphQL documentation
• Testing: Remove relevant tests

Implementation plan

• backend remove the followings;
  • VulnerabilityFindingDismiss GraphQL mutation
  • Vulnerabilities::FindingDismissService

Verification steps

• Verify that the mutation is not available on GraphQL
• Since this is a deprecation, just to make sure front end is not using this mutation, run e2e:package-and-test manual job in the MR pipeline and ensure green govern specs.