command-not-found: Simplify Homebrew on macOS setup

Now that 'command-not-found' helper loading has been significantly
simplified and the startup time improved in the official Homebrew tap,
the workaround for script detection (and caching) can be removed.

modules/command-not-found/init.zsh

@@ -13,30 +13,10 @@ if [[ -s '/etc/zsh_command_not_found' ]]; then
 elif [[ -s '/usr/share/doc/pkgfile/command-not-found.zsh' ]]; then
   source '/usr/share/doc/pkgfile/command-not-found.zsh'
 # Load command-not-found on macOS when Homebrew tap is configured.
-# To avoid performance penalty, we do not use Homebrew's ruby based command
-# lookup mechanism (viz., `brew command command-not-found-init`) and instead
-# `find` it ourselves from `TAP_DIRECTORY` defined internally in Homebrew.
-elif (( $+commands[brew] )); then
-  cnf_command=(
-    "$(brew --repository 2> /dev/null)"/Library/Taps/*/*/cmd/brew-command-not-found-init(|.rb)(.N)
-  )
-  if (( $#cnf_command )); then
-    cache_file="${XDG_CACHE_HOME:-$HOME/.cache}/prezto/brew-command-not-found-cache.zsh"
-
-    if [[ "${${(@o)cnf_command}[1]}" -nt "$cache_file" \
-          || "${ZDOTDIR:-$HOME}/.zpreztorc" -nt "$cache_file" \
-          || ! -s "$cache_file" ]]; then
-      mkdir -p "$cache_file:h"
-      # brew command-not-found-init is slow; cache its output.
-      brew command-not-found-init >! "$cache_file" 2> /dev/null
-    fi
-
-    source "$cache_file"
-
-    unset cache_file
-  fi
-
-  unset cnf_command
+elif (( $+commands[brew] )) \
+      && [[ -s "${hb_cnf_handler::="$(brew --repository 2> /dev/null)"/Library/Taps/homebrew/homebrew-command-not-found/handler.sh}" ]]; then
+  source "$hb_cnf_handler"
+  unset hb_cnf_handler
 # Return if requirements are not found.
 else
   return 1