Drop obsolete experimentalDecorators #11918

Because we don't use parameter decorators anymore, so we don't need it.

Author: PowerKiKi

tsconfig.json

@@ -15,7 +15,6 @@
         "noFallthroughCasesInSwitch": true,
         "skipLibCheck": true,
         "isolatedModules": true,
-        "experimentalDecorators": true,
         "importHelpers": true,
         "target": "ES2022",
         "module": "preserve"