send userData for user_online as well

This is a bit wrong, since each client can have its own userData.
user_online will have the first client's userData. (Or the first one
redis decides to read from the hash.)

/cc @zendesk/zendesk-radar


### Steps to merge
 - [ ] :+1: of the team

### References
 - Jira link: 

### Risks
 - None