ruby-syntax-methods-before-regexp: Drop this whitelist

ruby-syntax-methods-before-regexp: Drop this whitelist

* lisp/progmodes/ruby-mode.el (ruby-syntax-before-regexp-re):
Match only based on keywords and operators.
(ruby-syntax-methods-before-regexp): Delete.
(ruby-syntax-propertize): Use the new heuristic based on spaces
instead of checking for method names before (bug#67569).

* test/lisp/progmodes/ruby-mode-tests.el
(ruby-regexp-not-division-when-only-space-before):
Use non-whitelisted method name.

* test/lisp/progmodes/ruby-mode-resources/ruby.rb:
Adjust two examples.