Cleanup service plist code.

Library/Homebrew/formula.rb

@@ -970,9 +970,9 @@ class Formula
 
   # The service specification of the software.
   def service
-    return Homebrew::Service.new(self, &self.class.service) if service?
+    return unless service?
 
-    nil
+    Homebrew::Service.new(self, &self.class.service)
   end
 
   # @private

Library/Homebrew/service.rb

@@ -111,14 +111,7 @@ module Homebrew
       end
     end
 
-    delegate [ # rubocop:disable Layout/HashAlignment
-      :bin,
-      :var,
-      :etc,
-      :opt_bin,
-      :opt_sbin,
-      :opt_prefix,
-    ] => :@formula
+    delegate [:bin, :var, :etc, :opt_bin, :opt_sbin, :opt_prefix] => :@formula
 
     sig { returns(String) }
     def std_service_path_env