Remove outline-cycle-minor-mode and outline-cycle-highlight-minor-mode

Remove outline-cycle-minor-mode and outline-cycle-highlight-minor-mode

* lisp/outline.el (outline-font-lock-keywords): Use OVERRIDE or
LAXMATCH depending on outline-minor-mode-highlight in outline-minor-mode.
(outline-minor-mode-cycle, outline-minor-mode-highlight): Promote
defvar to defcustom.
(outline-minor-mode-highlight-buffer): Don't override existing faces.
(outline-cycle-minor-mode, outline-cycle-highlight-minor-mode):
Remove minor modes.

* etc/compilation.txt:
* etc/grep.txt: Enable outline-minor-mode-cycle and
outline-minor-mode-highlight with outline-minor-mode.
https://lists.gnu.org/archive/html/emacs-devel/2021-03/msg00144.html