Remove usage of DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER

What does this MR do?

Following Remove gemnasium-gradle-plugin and DS_EXPERIMEN... (gitlab-org/gitlab#437278 - closed) • Philip Cunningham • 17.1 • On track, this env var is no longer relevant.

What are the relevant issue numbers?

Remove gemnasium-gradle-plugin and DS_EXPERIMEN... (gitlab-org/gitlab#437278 - closed) • Philip Cunningham • 17.1 • On track.

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Ensure the report version matches the equivalent schema version
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer