Update very outdated SAST report fixtures

Proposal

The report fixtures we use within the rails application are very, very old. They do not test real-world conditions and have a high likelihood of hiding bugs.

This also appears to be true for ~"Category:Dependency Scanning" and should be updated as well.

Implementation Plan

1. Remove https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/fixtures/security_reports/master/gl-sast-report.json (wrong namespace) this actually makes sense as we're moving more of SAST to core
2. Add https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/spec/fixtures/security_reports/master/gl-sast-report.json
3. Update https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/spec/fixtures/security_reports/feature_branch/gl-sast-report.json
4. Update all failing tests