Default on :cluster_vulnerabilities feature flag

- change default from false to true

Changelog: changed

config/feature_flags/development/cluster_vulnerabilities.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/343917
 milestone: '14.5'
 type: development
 group: group::container security
-default_enabled: false
+default_enabled: true