DashboardSchema: Remove old unused legacy props style and timepicker.enable (#73879)

* DashboardScheam: Remove old unused legacy props style and timepicker.enable

* Update

* fix test

pkg/services/alerting/testdata/collapsed-panels.json

@@ -556,7 +556,6 @@
     }
   ],
   "schemaVersion": 16,
-  "style": "dark",
   "tags": [],
   "templating": {
     "list": []

pkg/services/alerting/testdata/dash-without-id.json

@@ -3,8 +3,7 @@
     "tags": [
       "apa"
     ],
-    "style": "dark",
-    "timezone": "browser",
+      "timezone": "browser",
     "editable": true,
     "sharedCrosshair": false,
     "rows": [

pkg/services/alerting/testdata/influxdb-alert.json

@@ -4,8 +4,7 @@
     "tags": [
       "apa"
     ],
-    "style": "dark",
-    "timezone": "browser",
+      "timezone": "browser",
     "editable": true,
     "sharedCrosshair": false,
     "rows": [

pkg/services/alerting/testdata/panel-with-bad-query-id.json

@@ -168,7 +168,6 @@
     }
   ],
   "schemaVersion": 27,
-  "style": "dark",
   "tags": [],
   "templating": {
     "list": []

pkg/services/alerting/testdata/panel-without-specified-datasource.json

@@ -168,7 +168,6 @@
     }
   ],
   "schemaVersion": 27,
-  "style": "dark",
   "tags": [],
   "templating": {
     "list": []