fix flaky SmsDispatcherControllerTest

flaky test is likely due to the short wait time. SmsDispatcherController
might not handle the Ims Network state change yet, so it still think the
underlying tech is Cdma or Gsm rather than ImsGsmSms/ImsCdmaSms. The fix
is using waitForHandlerAction which is more deterministic.

Bug: 78358733
Test: runtest SmsDispatcherControllerTest
Change-Id: Ibb5a2022278eee288f12d2f025cf7e34516d0114