feat(gitlab): Add API pipleine flag (#112367)

Part of [VDY-39: GitLab: API-driven integration
setup](https://linear.app/getsentry/issue/VDY-39/gitlab-api-driven-integration-setup)

Author: evanpurkhiser

src/sentry/features/temporary.py

@@ -143,6 +143,7 @@ def register_temporary_features(manager: FeatureManager) -> None:
     manager.add("organizations:scm-source-context", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # API-driven integration setup pipeline (per-provider rollout)
     manager.add("organizations:integration-api-pipeline-github", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
+    manager.add("organizations:integration-api-pipeline-gitlab", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Project Management Integrations Feature Parity Flags
     manager.add("organizations:integrations-github_enterprise-project-management", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     manager.add("organizations:integrations-gitlab-project-management", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)