feat(core): Set up leader selection for multiple main instances (#7527)

https://linear.app/n8n/issue/PAY-933/set-up-leader-selection-for-multiple-main-instances

- [x] Set up new envs
- [x] Add config and license checks
- [x] Implement `MultiMainInstancePublisher`
- [x] Expand `RedisServicePubSubPublisher` to support
`MultiMainInstancePublisher`
- [x] Init `MultiMainInstancePublisher` on startup and destroy on
shutdown
- [x] Add to sandbox plans
- [x] Test manually

Note: This is only for setup - coordinating in reaction to leadership
changes will come in later PRs.

packages/cli/src/controllers/e2e.controller.ts

@@ -67,6 +67,7 @@ export class E2EController {
 		[LICENSE_FEATURES.WORKFLOW_HISTORY]: false,
 		[LICENSE_FEATURES.DEBUG_IN_EDITOR]: false,
 		[LICENSE_FEATURES.BINARY_DATA_S3]: false,
+		[LICENSE_FEATURES.MULTIPLE_MAIN_INSTANCES]: false,
 	};
 
 	constructor(