Remove bogus ":safe nil" custom properties

Remove bogus ":safe nil" custom properties

* lisp/org/oc.el (org-cite-activate-processor)
(org-cite-export-processors, org-cite-follow-processor)
(org-cite-insert-processor):
* lisp/org/ol.el (org-link-parameters, org-link-frame-setup)
(org-link-shell-confirm-function)
(org-link-shell-skip-confirm-regexp)
(org-link-elisp-confirm-function)
(org-link-elisp-skip-confirm-regexp):
* lisp/org/org-num.el (org-num-format-function):
Remove bogus ":safe nil" that do nothing but propagate a
misunderstanding of the safe-local-variable property.