(maint) Ensure $VERBOSE is restored

If the block passed to `with_verbose_disabled` raised, then $VERBOSE wasn't
restored to its original value. This method isn't used in puppet, but has been
here a long time, so guard against the issue instead of removing the method.

spec/lib/puppet_spec/verbose.rb

@@ -2,9 +2,11 @@
 module Kernel
   def with_verbose_disabled
     verbose, $VERBOSE = $VERBOSE, nil
-    result = yield
-    $VERBOSE = verbose
-    return result
+    begin
+      yield
+    ensure
+      $VERBOSE = verbose
+    end
   end
 
   def with_verbose_enabled