refactor(telemetry): rename dashboard template variable label from 'Service' to 'Service Name'

Continuation of the same rename applied on phase-6-statsd (commit
91c6582bd5): 5 more dashboards introduced on phase-7 (formerly the
system-* set, renamed to bare names by 2c590a47c5) still carried the
older 'Service' UI label. Aligning them with the rest.

Same reasoning as the phase-6 commit: the underlying Prometheus label
is `service_name`, and the UI label 'Service' misled users into typing
`service=xrpld` in Grafana Metrics Drilldown.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docker/telemetry/grafana/dashboards/ledger-data-sync.json

@@ -498,7 +498,7 @@
     "list": [
       {
         "name": "service_name",
-        "label": "Service",
+        "label": "Service Name",
         "description": "Filter by service.name (e.g. xrpld, xrpld-validator)",
         "type": "query",
         "query": "label_values(service_name)",

docker/telemetry/grafana/dashboards/network-traffic.json

@@ -776,7 +776,7 @@
     "list": [
       {
         "name": "service_name",
-        "label": "Service",
+        "label": "Service Name",
         "description": "Filter by service.name (e.g. xrpld, xrpld-validator)",
         "type": "query",
         "query": "label_values(service_name)",

docker/telemetry/grafana/dashboards/node-health.json

@@ -898,7 +898,7 @@
     "list": [
       {
         "name": "service_name",
-        "label": "Service",
+        "label": "Service Name",
         "description": "Filter by service.name (e.g. xrpld, xrpld-validator)",
         "type": "query",
         "query": "label_values(service_name)",

docker/telemetry/grafana/dashboards/overlay-traffic-detail.json

@@ -558,7 +558,7 @@
     "list": [
       {
         "name": "service_name",
-        "label": "Service",
+        "label": "Service Name",
         "description": "Filter by service.name (e.g. xrpld, xrpld-validator)",
         "type": "query",
         "query": "label_values(service_name)",

docker/telemetry/grafana/dashboards/rpc-pathfinding.json

@@ -597,7 +597,7 @@
     "list": [
       {
         "name": "service_name",
-        "label": "Service",
+        "label": "Service Name",
         "description": "Filter by service.name (e.g. xrpld, xrpld-validator)",
         "type": "query",
         "query": "label_values(service_name)",