Add needed tests to validate the OEQA Threaded mode, the remaining
parts are tested by the OEQA without Threaded mode.
- test_loader.py: Add a test to validate rules when creating the
list of test suites.
- test_decorators.py: Add oetimeout test because the threaded mode
uses Timer instead of signal.
[YOCTO #11450]
Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>