chore(ui): remove the deprecated Learning Resources sidebar link (#51251)

Learning Resources is on the finalized deprecation list in
https://github.com/BerriAI/litellm/discussions/32090 for low usage, with no
replacement. Drop its Developer Tools entry, the now unused BookOpen icon
import, its page description mapping and both en.json strings, and take it
out of the top-level label list in leftnav.test.tsx.

ui/litellm-dashboard/src/components/leftnav.test.tsx

@@ -284,7 +284,6 @@ describe("Sidebar (leftnav)", () => {
       "Budgets",
       "API Reference",
       "AI Hub",
-      "Learning Resources",
       "Experimental",
       "Settings",
     ];

ui/litellm-dashboard/src/components/leftnav.tsx

@@ -25,7 +25,6 @@ import {
   Bell,
   Blocks,
   Bot,
-  BookOpen,
   Building2,
   Boxes,
   ChevronRight,
@@ -434,13 +433,6 @@ const menuGroups: MenuGroup[] = [
         label: "shell.nav.items.aiHub",
         icon: <LayoutGrid {...ICON} />,
       },
-      {
-        key: "learning-resources",
-        page: "learning-resources",
-        label: "shell.nav.items.learningResources",
-        icon: <BookOpen {...ICON} />,
-        external_url: "https://models.litellm.ai/cookbook",
-      },
       {
         key: "caching",
         page: "caching",

ui/litellm-dashboard/src/components/page_metadata.ts

@@ -36,7 +36,6 @@ export const pageDescriptions: Record<string, ParseKeys> = {
   budgets: "shell.pageDescriptions.budgets",
   api_ref: "shell.pageDescriptions.apiRef",
   "model-hub-table": "shell.pageDescriptions.modelHubTable",
-  "learning-resources": "shell.pageDescriptions.learningResources",
   caching: "shell.pageDescriptions.caching",
   "transform-request": "shell.pageDescriptions.transformRequest",
   "cost-tracking": "shell.pageDescriptions.costTracking",

ui/litellm-dashboard/src/i18n/locales/en.json

@@ -8037,7 +8037,6 @@
         "budgets": "Budgets",
         "apiReference": "API Reference",
         "aiHub": "AI Hub",
-        "learningResources": "Learning Resources",
         "responseCache": "Response Cache",
         "experimental": "Experimental",
         "prompts": "Prompts",
@@ -8085,7 +8084,6 @@
       "budgets": "Set and monitor spending budgets",
       "apiRef": "Browse API documentation and endpoints",
       "modelHubTable": "Explore available AI models and providers",
-      "learningResources": "Access tutorials and documentation",
       "caching": "Configure response caching and coordination Redis settings",
       "transformRequest": "Set up request transformation rules",
       "costTracking": "Track and analyze API costs",