kernel: Further unify _reschedule APIs

Now that other work has eliminated the two cases where we had to do a
reschedule "but yield even if we are cooperative", we can squash both
down to a single _reschedule() function which does almost exactly what
legacy _Swap() did, but wrapped as a proper scheduler API.

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

kernel/thread_abort.c

@@ -46,7 +46,7 @@ void _impl_k_thread_abort(k_tid_t thread)
 		}
 
 		/* The abort handler might have altered the ready queue. */
-		_reschedule_noyield(key);
+		_reschedule(key);
 	}
 }
 #endif