fix: remove stale bats test file re-added by revert

The revert commit brought back tests-old-controller.bats, but upstream
converted all bats tests to ginkgo. The ginkgo equivalent
(e2e/test/compat_old_controller_test.go) is the canonical test file.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: raballew