Disable broken webgoat and distroless tests for grype

Why is this change being made?

The webgoat and distroless integration tests are currently broken for grype, because the grype-db has been updated, and a large number of vulnerabilities have been removed. We're currently investigating the issue in Grype container scan not returning vulnerabilit... (gitlab-org/gitlab#396285 - closed), however, in order to unblock other container scanning issues, we should disable these tests until we have a chance to figure out exactly what's going on.