selftests: tc-testing: move auxiliary scripts to a dedicated folder

Some taprio tests need auxiliary scripts to wait for workqueue events to
process. Move them to a dedicated folder in order to package them for
the kselftests tarball.

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://lore.kernel.org/r/20231017152309.3196320-3-pctammela@mojatatu.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>