Hi,
as you’ve already noticed, short-lived branches and pull requests have a hardcoded / builtin Quality Gate (no new bugs, vulnerabilities and code smells). Real Quality Gates for short-lived branches and PRs are coming soon with the next version Sonarqube 7.7, see Real Quality Gates for PRs and short-lived branches
The build breaker plugin is a third party plugin, not provided by Sonarsource with last release in 2017.
WIth newer Sonarqube versions you should use the webhook feature in your pipelines instead.
Regards,
Gilbert