Dev: Sets preserveSymlinks to false in top-level tsconfig (grafana#19395)

* Dev: Sets `preserveSymlinks` to `false` in top-level tsconfig
Improves dev experience in vscode

* Removed preserveSymlinks from tsconfig since default option is false

Author: kaydelaney

tsconfig.json

@@ -34,8 +34,7 @@
       "sass": ["sass"],
       "@grafana/slate-react": ["../node_modules/@types/slate-react"]
     },
-    "skipLibCheck": true,
-    "preserveSymlinks": true
+    "skipLibCheck": true
   },
   "include": [
     "public/app/**/*.ts",