[receiver/apache] send port number as an attribute

[aboguszewski-sumo]

Is your feature request related to a problem? Please describe.

Currently, the receiver only sends the server's name (which is the hostname) as an attribute. It would be useful to send also the port (for example, Sumo Logic app for Apache uses it).
The important thing to note here is that the port can't be deduced solely from the endpoint - the default port is different when we use http (80) and when we use https (443).

Describe the solution you'd like

An additional attribute should be sent with the metrics.
The solution will be short and easy to implement, here is how Telegraf does it: https://github.com/influxdata/telegraf/blob/master/plugins/inputs/apache/apache.go#L190

Describe alternatives you've considered

No response

Additional context

The hostname is currently being sent as a separate attribute, not a resource attribute - it would be cool to change that, but I'm not sure if it should be done in the same PR. I'm not sure, how to add the port here. Ideally, I think that both attributes should be resource attributes. If we shouldn't change now how the hostname is sent, should the port be sent as a normal attribute (to keep the convention) or as a resource attribute (as it actually should be)?

[github-actions]

Pinging code owners: @djaglowski. See Adding Labels via Comments if you do not have permissions to add labels yourself.

[djaglowski]

I agree that both hostname and port should be a resource attributes. The changes should be made in separate PRs, but we should try to get them both into the same release.

[aboguszewski-sumo]

If I'm not mistaken, the next release (0.62) will be this Friday? Since Elasticsearch metrics have more priority for now, I will add these changes for 0.63.

[aboguszewski-sumo]

I've created a commit for port as well, I will rebase it and create a PR as soon as #14926 gets merged.

[aboguszewski-sumo]

The changes have been merged, but they are behind feature gates. I don't know what's the policy here, but I suggest to leave this issue open until the feature gates are gone.

[aboguszewski-sumo]

This will be resolved once #17355 gets merged.