cleanup: ignore DS_Store access failures.

Fixes #10988.

Library/Homebrew/cleanup.rb

@@ -435,7 +435,12 @@ module Homebrew
       ]
       dirs.select(&:directory?)
           .flat_map { |d| Pathname.glob("#{d}/**/.DS_Store") }
-          .each(&:unlink)
+          .each do |dir|
+            dir.unlink
+          rescue Errno::EACCES
+            # don't care if we can't delete a .DS_Store
+            nil
+          end
     end
 
     def prune_prefix_symlinks_and_directories