Remove Emacs 25 compatibility from Tramp

Remove Emacs 25 compatibility from Tramp

* doc/misc/tramp.texi (Remote programs, Remote processes)
(Frequently Asked Questions): Adapt Emacs versions.

* doc/misc/trampver.texi:
* lisp/net/trampver.el: Change version to "2.6.0-pre".

* lisp/net/tramp-adb.el (top): Don't use `tramp-compat-funcall' for
connection-local functions.

* lisp/net/tramp-compat.el (tramp-unload-file-name-handlers)
(tramp-handle-temporary-file-directory)
(tramp-compat-temporary-file-directory-function)
(tramp-compat-file-attribute-type)
(tramp-compat-file-attribute-link-number)
(tramp-compat-file-attribute-user-id)
(tramp-compat-file-attribute-group-id)
(tramp-compat-file-attribute-access-time)
(tramp-compat-file-attribute-modification-time)
(tramp-compat-file-attribute-status-change-time)
(tramp-compat-file-attribute-size)
(tramp-compat-file-attribute-modes, tramp-file-missing)
(tramp-compat-file-missing, tramp-compat-file-local-name): Remove.
(tramp-compat-file-name-quoted-p, tramp-compat-file-name-quote)
(tramp-compat-file-name-unquote)
(tramp-compat-progress-reporter-update)
(tramp-compat-file-modes, tramp-compat-set-file-modes)
(tramp-compat-set-file-times, tramp-compat-directory-files)
(tramp-compat-directory-files-and-attributes): Adapt implementation.

* lisp/net/tramp.el:
* lisp/net/tramp-adb.el:
* lisp/net/tramp-archive.el:
* lisp/net/tramp-crypt.el:
* lisp/net/tramp-fuse.el:
* lisp/net/tramp-gvfs.el:
* lisp/net/tramp-rclone.el:
* lisp/net/tramp-sh.el:
* lisp/net/tramp-smb.el:
* lisp/net/tramp-sudoedit.el: Adapt callees.

* lisp/net/tramp-crypt.el (tramp-crypt-config-file-name):
Expand file name.

* lisp/net/tramp-fuse.el (tramp-fuse-handle-file-readable-p): Remove.

* lisp/net/tramp-gvfs.el (tramp-gvfs-enabled): Don't check Emacs version.
(tramp-gvfs-handler-mounted-unmounted): Use `make-tramp-file-name'.

* lisp/net/tramp-integration.el (rfn-eshadow-overlay):
Remove declaration.
(top): Don't use `tramp-compat-funcall' for connection-local functions.

* lisp/net/tramp-rclone.el (tramp-rclone-file-name-handler-alist):
Use `tramp-rclone-handle-file-readable-p'.
(tramp-rclone-handle-file-readable-p): New defun.

* lisp/net/tramp-sshfs.el (tramp-sshfs-file-name-handler-alist):
Use `tramp-handle-file-readable-p'.

* lisp/net/tramp.el (tramp-temp-name-prefix, tramp-lookup-syntax):
Adapt docstring.
(tramp-set-connection-local-variables)
(tramp-set-connection-local-variables-for-buffer): Don't use
`tramp-compat-funcall' for connection-local functions.
(tramp-file-name-for-operation): Reorder list.
(tramp-handle-make-symbolic-link): Don't handle TARGET and
OK-IF-ALREADY-EXISTS.
(tramp-read-passwd): Don't use `read-passwd' any longer.
(top): Don't check for `interrupt-process-functions'.

* test/lisp/net/tramp-archive-tests.el (tramp-archive--test-emacs26-p):
Remove.
(tramp-archive-test02-file-name-dissect): Use `make-tramp-file-name'.
(all): Replace Emacs 26 compatibility functions with their
original name.
(tramp-archive-test46-auto-load)
(tramp-archive-test46-delay-load): Rename.

* test/lisp/net/tramp-tests.el (dired-aux, seq): Require them.
(dired-compress, connection-local-criteria-alist)
(connection-local-profile-alist, async-shell-command-width):
Don't declare.
(all): Replace Emacs 26 compatibility functions with their
original name.
(tramp-test04-substitute-in-file-name)
(tramp-test10-write-region, tramp-test11-copy-file)
(tramp-test12-rename-file, tramp-test15-copy-directory)
(tramp-test17-insert-directory)
(tramp-test17-dired-with-wildcards, tramp-test21-file-links)
(tramp-test31-interrupt-process)
(tramp-test34-connection-local-variables)
(tramp-test34-explicit-shell-file-name)
(tramp-test40-make-nearby-temp-file)
(tramp-test41-special-characters, tramp-test42-utf8)
(tramp-test46-delay-load, tramp-test46-remote-load-path)
(tramp-test47-unload): Don't check for Emacs 26 special features.
(tramp--test-emacs26-p): Remove.
(tramp--test-emacs29-p): New defun.
(tramp-test45-dired-compress-file)
(tramp-test45-dired-compress-dir): Use it.
(tramp-test44-asynchronous-requests): Use `seq-random-elt'.