update existing documentation about possible values for Severity to denote depreciation of Undefined and document the mapping for each analyzer

Problem to solve

Today we use a similar vocabulary for communicating Severity and Confidence. This leads to a confusing experience, especially where the two labels appear near to one another.

Epic:Security reports: Remodel severity levels

Epic:Security reports: Remodel severity and confidence

Intended users

• Delaney (Development Team Lead)
• Sasha (Software Developer)
• Devon (DevOps Engineer)
• Sidney (Systems Administrator)
• Sam (Security Analyst)

Further details

Proposal

update existing documentation about depreciation of Undefined, and all possible values for Severity mapping for each analyzer

Implementation plan

• remove all mentions of Undefined in all our documentation or merge content with Unknown when relevant.
  • https://docs.gitlab.com/ee/api/vulnerability_findings.html#list-project-vulnerability-findings
  • https://docs.gitlab.com/ee/user/application_security/container_scanning/#reports-json-format
  • https://docs.gitlab.com/ee/user/application_security/dependency_scanning/#reports-json-format
  • https://docs.gitlab.com/ee/user/application_security/sast/#reports-json-format

Documentation

Check if any screen shots or other elements of related documentation need updates

Availability & Testing

Verify if tests pass or need updates as a result

Links / references