Revert "Rewrite journey routes formatter for performance"

This reverts commit 5c224de9e110763ec7a0f01f5b604bcf81f40bfb.

Conflicts:
	actionpack/lib/action_dispatch/journey/visitors.rb

5c224de9e110763ec7a0f01f5b604bcf81f40bfb introduced a bug in the
formatter.  This commit includes a regression test.