Add health status metrics for dedicated servers

[joanmassachs-wikiloc]

Before this commit, health status was only collected for cloud servers,
that are identified by their server id. This commit adds support also
for dedicated servers, that are identified by their IP.

Example dedicated server target in API response:

            "targets": [
                {
                    "ip": {
                        "ip": "10.0.1.1"
                    },
                    "health_status": [
                        {
                            "listen_port": 80,
                            "status": "healthy"
                        }
                    ],
                    "type": "ip"
                }
            ],

I have also included a second commit to use "ENV key=value" in Dockerfile instead of legacy "ENV key value" as explained in https://docs.docker.com/go/dockerfile/rule/legacy-key-value-format/.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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