Tramp code cleanup

Tramp code cleanup

* lisp/net/tramp-cache.el (tramp-get-file-property)
(tramp-get-connection-property): Make DEFAULT optional.  Adapt callees.

* lisp/net/tramp.el:
* lisp/net/tramp-adb.el:
* lisp/net/tramp-cmds.el:
* lisp/net/tramp-compat.el:
* lisp/net/tramp-crypt.el:
* lisp/net/tramp-ftp.el:
* lisp/net/tramp-fuse.el:
* lisp/net/tramp-gvfs.el:
* lisp/net/tramp-integration.el:
* lisp/net/tramp-sh.el:
* lisp/net/tramp-smb.el:
* lisp/net/tramp-sshfs.el:
* lisp/net/trampver.el: Code cleanup.

* test/lisp/net/tramp-tests.el (tramp--test-sh-no-ls--dired-p)
(tramp--test-with-proper-process-name-and-buffer): Code cleanup.