Prefer defcustom :local specifier in textmodes

Prefer defcustom :local specifier in textmodes

* lisp/textmodes/fill.el (default-justification):
* lisp/textmodes/ispell.el (ispell-local-dictionary)
(ispell-skip-html):
* lisp/textmodes/less-css-mode.el (less-css-output-file-name)
(less-css-input-file-name):
* lisp/textmodes/refer.el (refer-bib-directory, refer-bib-files)
(refer-cache-bib-files):
* lisp/textmodes/two-column.el (2C-separator, 2C-window-width):
Prefer defcustom :local specifier to using 'make-variable-buffer-local'
directly.

(cherry picked from commit 4bb62af3263057312021e076dc7e0c8ff195e38f)