Set stable default variable selections for key dashboards

GBarmUB/gbarmub-node-exporter.json

@@ -15667,7 +15667,11 @@
     "templating": {
       "list": [
         {
-          "current": {},
+          "current": {
+            "selected": true,
+            "text": "prometheus",
+            "value": "ff1qkncht70n4c"
+          },
           "includeAll": false,
           "label": "Datasource",
           "name": "ds_prometheus",
@@ -15678,7 +15682,11 @@
           "type": "datasource"
         },
         {
-          "current": {},
+          "current": {
+            "selected": true,
+            "text": "linux",
+            "value": "linux"
+          },
           "datasource": {
             "type": "prometheus",
             "uid": "${ds_prometheus}"
@@ -15698,7 +15706,11 @@
           "type": "query"
         },
         {
-          "current": {},
+          "current": {
+            "selected": true,
+            "text": "armub",
+            "value": "armub"
+          },
           "datasource": {
             "type": "prometheus",
             "uid": "${ds_prometheus}"
@@ -15718,7 +15730,11 @@
           "type": "query"
         },
         {
-          "current": {},
+          "current": {
+            "selected": true,
+            "text": "192.168.50.4:9100",
+            "value": "192.168.50.4:9100"
+          },
           "datasource": {
             "type": "prometheus",
             "uid": "${ds_prometheus}"