fix(ivy): ensure flx is loaded with (ivy +fuzzy)

Overriding `ivy--flx-featurep` here would always prevent flx from being
loaded and enabled---even if it were `t`---because ivy `require`s it in
`ivy--flx-featurep`'s initvalue. So instead, this sets the variable if
and only if it should be disabled. Because flx isn't installed when
+prescient is enabled, I've included that in the condition for disabling
ivy--flx-featurep as well

Fix: https://github.com/doomemacs/doomemacs/issues/6034
Amend: bae7ab0d8d

modules/completion/ivy/config.el

@@ -372,7 +372,9 @@ results buffer.")
   :when (modulep! +fuzzy)
   :unless (modulep! +prescient)
   :defer t  ; is loaded by ivy
-  :preface (setq ivy--flx-featurep (modulep! +fuzzy))
+  :preface (when (or (not (modulep! +fuzzy))
+                     (modulep! +prescient))
+             (setq ivy--flx-featurep nil))
   :init (setq ivy-flx-limit 10000))
 
 (use-package! ivy-avy