Merge pull request #16368 from Kentzo/prefer_sudo_as_root

sudo: Prioritize sudo_as_root over HOMEBREW_SUDO_THROUGH_SUDO_USER.

Library/Homebrew/system_command.rb

@@ -190,9 +190,8 @@ class SystemCommand
                      *askpass_flags,
                      "-E", *env_args,
                      "--", "/usr/bin/sudo"]
-    elsif sudo_as_root?
-      user_flags += ["-u", "root"]
     end
+    user_flags += ["-u", "root"] if sudo_as_root?
     ["/usr/bin/sudo", *user_flags, *askpass_flags, "-E", *env_args, "--"]
   end