Default completion-flex-nospace to nil

By default, the flex completion style _does_ match spaces.

Fixes: bug#40625

* lisp/icomplete.el (icomplete--fido-mode-setup): Force
completion-flex-nospace to nil.

* lisp/minibuffer.el (completion-flex-nospace): Default to nil.

lisp/icomplete.el

@@ -329,6 +329,7 @@ if that doesn't produce a completion match."
                 icomplete-show-matches-on-no-input t
                 icomplete-hide-common-prefix nil
                 completion-styles '(flex)
+                completion-flex-nospace nil
                 completion-category-defaults nil)))
 
 ;;;###autoload

lisp/minibuffer.el

@@ -3607,7 +3607,7 @@ that is non-nil."
 ;;; "flex" completion, also known as flx/fuzzy/scatter completion
 ;; Completes "foo" to "frodo" and "farfromsober"
 
-(defcustom completion-flex-nospace t
+(defcustom completion-flex-nospace nil
   "Non-nil if `flex' completion rejects spaces in search pattern."
   :version "27.1"
   :type 'boolean)