Revert "build: fix warning in cares under GN build"

This reverts commit f22802c.

PR-URL: #51865
Reviewed-By: Vinícius Lourenço Claro Cardoso <[email protected]>

Author: lpinca

deps/cares/unofficial.gni

@@ -69,8 +69,6 @@ template("cares_gn_build") {
       cflags_c = [
         "-Wno-implicit-fallthrough",
         "-Wno-unreachable-code",
-        # Remove after https://github.com/c-ares/c-ares/pull/709 lands in Node.
-        "-Wno-unused-result",
       ]
     }
   }