fix(tazjin/emacs): Set notmuch custom variables through :custom

It seems like some of them end up file-local anyways, and the explicit
call to `custom-set-variables` in mail-setup.el had seemingly no effect.

Change-Id: Iad5011b5f8348b1ca5973813995c9644ac85ddf5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2610
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/emacs/config/init.el

@@ -78,10 +78,10 @@
 (use-package multiple-cursors)
 
 (use-package notmuch
-  :config
-  (setq notmuch-search-oldest-first nil)
-  (setq notmuch-show-all-tags-list t)
-  (setq notmuch-hello-tag-list-make-query "tag:unread"))
+  :custom
+  (notmuch-search-oldest-first nil)
+  (notmuch-show-all-tags-list t)
+  (notmuch-hello-tag-list-make-query "tag:unread"))
 
 (use-package paredit :hook ((lisp-mode . paredit-mode)
                             (emacs-lisp-mode . paredit-mode)))

users/tazjin/emacs/config/mail-setup.el

@@ -22,7 +22,6 @@
       '((:name "inbox" :query "tag:inbox" :count-query "tag:inbox AND tag:unread" :key "i")
         (:name "sent" :query "tag:sent" :key "t")
         (:name "drafts" :query "tag:draft")))
-(custom-set-variables '(notmuch-search-oldest-first nil))
 (setq notmuch-show-empty-saved-searches t)
 
 ;; Mail sending configuration