tests: Remove memory leak checking infrastructure

There are far better ways to detect memory leaks, such as either
valgrind or ASan. Having Meson makes it really easy to use these tools
in our tests, and we can do that in CI as well.

Having these local wrappers actually completely broke ASan usage, so
remove them in favour of using the more powerful options.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>