tree-wide: fix some double word errors like "the the"

By chance (because I had this mistake in my own commit) I noticed
that there are a bunch of duplicated works like "the the" in the
code and man-pages.

This commit fixes them and some similar issues with "and and" etc.

src/core/namespace.c

@@ -2628,7 +2628,7 @@ int setup_namespace(const NamespaceParameters *p, char **reterr_path) {
                                 root_mount_fd = _root_mount_fd;
                         }
 
-                        /* Try to to clone the directory mount if we have privs to, so that we can apply the
+                        /* Try to clone the directory mount if we have privs to, so that we can apply the
                          * MS_SLAVE propagation settings right-away. */
                         if (root_mount_fd < 0) {
                                 _root_mount_fd = open_tree_attr_with_fallback(