tree-wide: use path_hash_ops instead of string_hash_ops whenever we key by a path

Let's make use of our new hash_ops!

src/shared/bus-unit-util.c

@@ -2369,7 +2369,7 @@ int unit_show_processes(
         if (r < 0)
                 return r;
 
-        cgroups = hashmap_new(&string_hash_ops);
+        cgroups = hashmap_new(&path_hash_ops);
         if (!cgroups)
                 return -ENOMEM;
 

src/shared/install.c

@@ -522,7 +522,7 @@ static int mark_symlink_for_removal(
 
         assert(p);
 
-        r = set_ensure_allocated(remove_symlinks_to, &string_hash_ops);
+        r = set_ensure_allocated(remove_symlinks_to, &path_hash_ops);
         if (r < 0)
                 return r;