test: clear tap instance caches between test runs again

The core taps exist outside of the normal cache busting cycle
so they need to clear explicitly at the instance level.
Just to be sure we should clear all of them each time.

This essentially reverts part of the change in this PR.
- https://github.com/Homebrew/brew/pull/16746

Library/Homebrew/test/spec_helper.rb

@@ -204,6 +204,7 @@ RSpec.configure do |config|
   config.around do |example|
     Homebrew.raise_deprecation_exceptions = true
 
+    Tap.each(&:clear_cache)
     Cachable::Registry.clear_all_caches
     FormulaInstaller.clear_attempted
     FormulaInstaller.clear_installed