tests/kernel/smp: Remove release_global_lock_irq case

This test case was taking a (traditional) irq_lock(), which masks
interrupts, and then calling k_mutex_lock() with a timeout of
K_FOREVER, which is a blocking call.  That's not legal, because it
will obviously schedule other threads to run in a context where the
code was promised it would not.  This used to be an uncaught error,
but now we have an assertion that catches this.

It's not clear what this test case is supposed to be testing, as the
behavior is actually identical to the release_global_lock case except
for the (incorrect) addition of the irq_lock().  If this is needed for
code coverage we can work to figure out the real root cause of the
missing coverage later.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>