Fix service check "topic" tag

[FlorianVeaux]

The mapr.can_connect service check is sent with the topic tag but in one place this tag is called topic_path. Let's fix the mistake.

Impact would be minimal as I doubt anyone tried to set up a monitor on mapr.can_connect by {topic_path}, knowing that:

• the backend doesn't know about that tag so you would have to create a custom check monitor instead of an integration monitor.
• This tag only appears when the MapR endpoint doesn't work.