Don't call 'kill-this-buffer' outside of menus

Don't call 'kill-this-buffer' outside of menus

* lisp/simple.el (kill-current-buffer): New function.
(completion-list-mode-map): Use it instead of kill-this-buffer.
* lisp/type-break.el (type-break-mode):
* lisp/term/ns-win.el (global-map):
* lisp/progmodes/gdb-mi.el (gdb-memory-mode-map)
(gdb-disassembly-mode-map, gdb-frames-mode-map)
(gdb-locals-mode-map, gdb-registers-mode-map):
* lisp/org/org-mhe.el (org-mhe-follow-link):
* lisp/net/secrets.el (secrets-mode-map):
* lisp/net/eudc.el (eudc-mode-map):
* lisp/net/eudc-hotlist.el (eudc-hotlist-mode-map): Use
kill-current-buffer instead of kill-this-buffer.  (Bug#26466)