Is setting `reftex-cite-format' in +ref.el necessary?

### Describe your request

Suggestion: Remove setting of `reftex-cite-format` in [+ref.el](https://github.com/hlissner/doom-emacs/blob/6bf725837def83acd140d9431d799c8b09abebf3/modules/lang/latex/%2Bref.el#L10).

The comment says:
https://github.com/hlissner/doom-emacs/blob/6bf725837def83acd140d9431d799c8b09abebf3/modules/lang/latex/%2Bref.el#L8-L10

RefTeX bundled with Emacs supports Biblatex commands since v26 (I think). The entry in [`reftex-cite-format-builtin`](http://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/textmodes/reftex-vars.el#n158) looks like this:

```elisp
(biblatex "The Biblatex package"
((?\C-m . "\\cite[][]{%l}")
(?C . "\\cite*[][]{%l}")
(?t . "\\textcite[][]{%l}")
(?T . "\\textcite*[][]{%l}")
(?p . "\\parencite[][]{%l}")
(?P . "\\parencite*[][]{%l}")
(?f . "\\footcite[][]{%l}")
(?s . "\\smartcite[][]{%l}")
(?u . "\\autocite[][]{%l}")
(?U . "\\autocite*[][]{%l}")
(?a . "\\citeauthor{%l}")
(?A . "\\citeauthor*{%l}")
(?i . "\\citetitle{%l}")
(?I . "\\citetitle*{%l}")
(?y . "\\citeyear{%l}")
(?Y . "\\citeyear*{%l}")
(?n . "\\nocite{%l}")))
```
which covers the important ones. Since Doom Emacs requires Emacs 27.1, I think there is no problem to use the built-in support.

If you agree with this change, you can also remove this line:
https://github.com/hlissner/doom-emacs/blob/6bf725837def83acd140d9431d799c8b09abebf3/modules/lang/latex/%2Bref.el#L23
to let AUCTeX activate the built-in version described above.

### Briefly explain its use-case

I think the built-in collection of commands is superior to the one suggested in the [answer](https://tex.stackexchange.com/a/31992/76063) referenced in +ref.el