A test executable can be declared with add_test_executable and never
registered with add_test. It is then built and never run, and ctest
reports a full pass over what it knows, so nothing in CI says so.
Measured on main, five test executables are in this state: the driver's
mesh and recorder tests, the guest formatting tests, the video out flip
tests and the BDA device tests.
tools/check_test_registration.py compares the test executables CMake
builds, read from the build graph, against the add_test calls in the
generated CTestTestfile.cmake files, which are written at configure time
and so do not depend on the build having finished. It fails on a test
executable that nothing runs, and records those five by name so the job
stays green until they are dealt with.
Both jobs run it right after configure, before anything is built.