fix: can't run multiple services on k8s (#3395)

Fix Issue: https://github.com/woodpecker-ci/woodpecker/issues/3288

The way the pod service starts up makes it impossible to run two or more
pipelines at the same time when we have a service section.

The idea is to set the name of the service in the same way we did for
the pod name.

Pipeline: 

```yaml

services:
  mydb:
    image: mysql
    environment:
      - MYSQL_DATABASE=test
      - MYSQL_ROOT_PASSWORD=example
    ports:
      - 3306/tcp
steps:
  get-version:
    image: ubuntu
    commands:
      - ( apt update && apt dist-upgrade -y && apt install -y mysql-client 2>&1 )> /dev/null
      - sleep 30s # need to wait for mysql-server init
      - echo 'SHOW VARIABLES LIKE "version"' | mysql -uroot -hmydb test -pexample
```

Running more than one pipeline result:


![image](https://github.com/woodpecker-ci/woodpecker/assets/22245125/e512309f-0d1e-4125-bab9-2357a710fedd)

---------

Co-authored-by: elias.souza <elias.souza@quintoandar.com.br>

pipeline/backend/kubernetes/pod.go

@@ -90,7 +90,7 @@ func podMeta(step *types.Step, config *config, options BackendOptions, podName s
 	}
 
 	if step.Type == types.StepTypeService {
-		meta.Labels[ServiceLabel] = step.Name
+		meta.Labels[ServiceLabel], _ = serviceName(step)
 	}
 
 	meta.Annotations = config.PodAnnotations