[v2] Don't use deprecated concat stdlib function

[jangaraj]

I'm getting warning:

{
"ts":"2025-02-27T15:25:52.518772427Z",
"level":"warn",
"msg":"this stdlib function is deprecated; please refer to the documentation for updated usage and alternatives",
"controller_path":"/",
"controller_id":"annotation_autodiscovery.feature",
"function":"concat"
}

It looks like concat is still used, for example:

k8s-monitoring-helm/charts/k8s-monitoring/charts/feature-annotation-autodiscovery/templates/_module.alloy.tpl

Line 190 in 280ea54

targets = concat(discovery.relabel.annotation_autodiscovery_pods.output, discovery.relabel.annotation_autodiscovery_services.output)

I think it should be replaced by array.concat instead.

[petewall]

PR in process.