test_translator: remove #![feature(nll)], stabilized in 1.63

Our old pinned nightly is 1.65, so this was already stabilized even back then.

Author: kkysen

scripts/test_translator.py

@@ -402,7 +402,6 @@ def run(self) -> List[TestOutcome]:
             "extern_types",
             "simd_ffi",
             "stdsimd",
-            "nll",
             "linkage",
             "register_tool",
         ])