Rename Gnus -unsubscribe-group commands to -toggle-subscription

* doc/emacs/misc.texi (Gnus Group Buffer): Document change.
* doc/misc/gnus.texi (Subscription Commands): Document change.
(Browse Foreign Server): Document change.
* lisp/gnus/gnus-group.el (gnus-group-mode-map):
Unsubscribe is not subscribe.
(gnus-group-sub-map): Unsubscribe is not subscribe.
(gnus-group-make-menu-bar): Unsubscribe is not subscribe.
(gnus-group-tool-bar-gnome): Unsubscribe is not subscribe.
(gnus-group-mode): Unsubscribe is not subscribe.
(gnus-group-unsubscribe): Refactor.
(gnus-group-subscribe): Refactor.
(gnus-group-unsubscribe-current-group): Define obsolete alias.
(gnus-group-unsubscribe-group): Define obsolete alias.
(gnus-group-toggle-subscription-at-point): Refactor.
(gnus-group-set-subscription-at-point): Refactor.
(gnus-group-toggle-subscription): Refactor.
(gnus-group-set-subscription): Refactor.
* lisp/gnus/gnus-srvr.el (gnus-browse-mode-map):
Unsubscribe is not subscribe.
(gnus-browse-make-menu-bar): Unsubscribe is not subscribe.
(gnus-browse-mode): Document the change.
(gnus-browse-unsubscribe-current-group): Define obsolete alias.
(gnus-browse-unsubscribe-group): Define obsolete alias.
(gnus-browse-toggle-subscription-at-point): Unsubscribe is not subscribe.
(gnus-browse-toggle-subscription): Unsubscribe is not subscribe
(bug#49759).
8 jobs for master in 12 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Prep Images
failed #24338
prep-image-base

00:00:12

 
  Build Images
skipped #24339
build-image-inotify
 
  Platform Images
skipped #24340
build-image-filenotify-gio
skipped #24341
build-image-gnustep
 
  Platforms
skipped #24342
test-filenotify-gio
skipped #24343
test-gnustep
 
  Native Comp Images
skipped #24344
build-native-bootstrap-speed0
 
  Slow
skipped #24345
test-all-inotify
 
Name Stage Failure
failed
prep-image-base Prep Images There has been a runner system failure, please try again
$ git config --global http.proxy $HTTP_PROXY; git config --global https.proxy $HTTPS_PROXY
Fetching changes with git depth set to 50...
Reinitialized existing Git repository in /builds/emacs/emacs/.git/
From https://emba.gnu.org/emacs/emacs
* [new ref] d6a3b1cd2b175d77bcfb24ac6ae047eb18b1bfcb -> refs/pipelines/11635
Checking out d6a3b1cd as master...

Skipping Git submodules setup
ERROR: Job failed (system failure): Error response from daemon: Conflict. The container name "/runner-2oEDrUT7-project-1-concurrent-1-build-4" is already in use by container "f46df44a43bee1f61a6ede2eac732a4e06eaa2094659f7ea23718f093d67bcc6". You have to remove (or rename) that container to be able to reuse that name. (executor_docker.go:726:0s)