Remove outdated debug_info test

Author: José Valim

lib/elixir/test/elixir/string_test.exs

@@ -553,10 +553,4 @@ defmodule StringTest do
     assert String.jaro_distance("jon", "john") == 0.9166666666666666
     assert String.jaro_distance("jon", "jan") == 0.7777777777777777
   end
-
-  test "skip debug_info in metadata modules" do
-    assert String.Unicode.__info__(:compile)[:options] == []
-    assert String.Graphemes.__info__(:compile)[:options] == []
-    assert String.Normalizer.__info__(:compile)[:options] == []
-  end
 end