L2SS-1054: fix datasource

dashboards/logs.json

 {
-    "__inputs": [
-      {
-        "name": "DS_LOKI",
-        "label": "Loki",
-        "description": "",
-        "type": "datasource",
-        "pluginId": "loki",
-        "pluginName": "Loki"
-      }
-    ],
-    "__elements": {},
-    "__requires": [
-      {
-        "type": "panel",
-        "id": "barchart",
-        "name": "Bar chart",
-        "version": ""
-      },
-      {
-        "type": "grafana",
-        "id": "grafana",
-        "name": "Grafana",
-        "version": "9.3.0-beta1"
-      },
-      {
-        "type": "panel",
-        "id": "logs",
-        "name": "Logs",
-        "version": ""
-      },
-      {
-        "type": "datasource",
-        "id": "loki",
-        "name": "Loki",
-        "version": "1.0.0"
-      }
-    ],
     "annotations": {
       "list": [
         {
@@ -68,7 +31,7 @@
       {
         "datasource": {
           "type": "loki",
-          "uid": "${DS_LOKI}"
+          "uid": "loki"
         },
         "fieldConfig": {
           "defaults": {
@@ -205,7 +168,7 @@
           {
             "datasource": {
               "type": "loki",
-              "uid": "${DS_LOKI}"
+              "uid": "loki"
             },
             "editorMode": "code",
             "expr": "rate({program=\"/home/tango/.local/bin/l2ss-$device\"} [$__interval])",
@@ -222,7 +185,7 @@
       {
         "datasource": {
           "type": "loki",
-          "uid": "${DS_LOKI}"
+          "uid": "loki"
         },
         "gridPos": {
           "h": 9,
@@ -245,7 +208,7 @@
           {
             "datasource": {
               "type": "loki",
-              "uid": "${DS_LOKI}"
+              "uid": "loki"
             },
             "editorMode": "code",
             "expr": "{program=\"/home/tango/.local/bin/l2ss-$device\"} |= `` | logfmt",