perf(core): Introduce concurrency control for main mode (#9453)

packages/cli/src/config/schema.ts

@@ -254,6 +254,15 @@ export const schema = {
 			env: 'EXECUTIONS_MODE',
 		},
 
+		concurrency: {
+			productionLimit: {
+				doc: "Max production executions allowed to run concurrently, in main process for regular mode and in worker for queue mode. Default for main mode is `-1` (disabled). Default for queue mode is taken from the worker's `--concurrency` flag.",
+				format: Number,
+				default: -1,
+				env: 'N8N_CONCURRENCY_PRODUCTION_LIMIT',
+			},
+		},
+
 		// A Workflow times out and gets canceled after this time (seconds).
 		// If the workflow is executed in the main process a soft timeout
 		// is executed (takes effect after the current node finishes).