Chore: Remove newBrowseDashboards feature toggle (#78190)

* remove all the things

* fix OldFolderPicker tests

* i18n

* remove more unused code

* remove mutation of error object since it's now frozen in the redux state

* fix error handling

public/locales/fr-FR/grafana.json

@@ -86,9 +86,7 @@
     "manage-folder-nav": {
       "alert-rules": "Règles d'alerte",
       "dashboards": "Tableaux de bord",
-      "panels": "Panneaux",
-      "permissions": "Permissions",
-      "settings": "Paramètres"
+      "panels": "Panneaux"
     },
     "new-folder-form": {
       "cancel-label": "Annuler",
@@ -1091,15 +1089,6 @@
       "new-dashboard": "Nouveau tableau de bord",
       "new-folder": "Nouveau dossier"
     },
-    "folder-view": {
-      "go-to-folder": "Aller dans le dossier",
-      "select-folder": "Sélectionner un dossier"
-    },
-    "result-kind": {
-      "dashboard": "Tableau de bord",
-      "folder": "Dossier",
-      "panel": "Panneau"
-    },
     "results-table": {
       "datasource-header": "Source de données",
       "location-header": "Emplacement",
@@ -1114,12 +1103,6 @@
       "placeholder": "Rechercher des tableaux de bord"
     }
   },
-  "search-view": {
-    "no-results": {
-      "clear": "Effacer la recherche et les filtres",
-      "text": "Aucun résultat trouvé pour votre requête."
-    }
-  },
   "share-modal": {
     "dashboard": {
       "title": "Partager"