Revert logs `service_name` preference of `container.name` vs `k8s.pod.name`

[cyrille-leclerc]

The logs service_name logic used to prioritize the value of container.name over k8s.pod.name before we started embracing the OpenTelemetry operator naming conventions for service.name (here) through the PR #1175 .

Unfortunately, as we haven't yet fully implemented the OTel Operator logic, not yet retrieving k8s.deployment.name, k8s.cronjob.name, or k8s.job.name, we end up too often with the logs service_name picking k8s.pod.name.

Waiting to fully implement the OTel Operator service name logic, we want to revert the previous behaviour and prioritize container.name over pod.name.

The logic is implemented in

k8s-monitoring-helm/charts/k8s-monitoring/charts/feature-pod-logs/templates/_common_pod_discovery.alloy.tpl

Lines 57 to 77 in 6ba1757

	// explicitly set service_name. if not set, loki will automatically try to populate a default.
	// see https://grafana.com/docs/loki/latest/get-started/labels/#default-labels-for-all-users
	//
	// choose the first value found from the following ordered list:
	// - pod.annotation[resource.opentelemetry.io/service.name]
	// - pod.label[app.kubernetes.io/name]
	// - k8s.pod.name
	// - k8s.container.name
	rule {
	action = "replace"
	source_labels = [
	"__meta_kubernetes_pod_annotation_resource_opentelemetry_io_service_name",
	"__meta_kubernetes_pod_label_app_kubernetes_io_name",
	"__meta_kubernetes_pod_name",
	"__meta_kubernetes_pod_container_name",
	]
	separator = ";"
	regex = "^(?:;*)?([^;]+).*$"
	replacement = "$1"
	target_label = "service_name"
	}