Heartbeat ports exported as string

[urso]

Just noticed port numbers in the json document exported by heartbeat are string, not numbers. See sample output from event refactoring: #4091

The fields.yml file already configures the port number to be an integer.

[ruflin]

I just tested this on master and it seems to be integer there now. Must be a change between 5.x and 6.x where we fixed this?

The initial thread where this popped up: https://discuss.elastic.co/t/what-type-is-the-port-field-in-heartbeat-output/108586/11

[elasticmachine]

Pinging @elastic/uptime

[andrewvc]

Given that it's fixed in 6.x I'm going to close this since 5.x isn't supported.