Resolve flaky call sequencing unit tests

With the recent changes made to the ECC logic for call sequencing,
additional waiting needs to be included for the reject verification.
This will resolve the flakiness found around these tests.

Bug: 401736961
Flag: EXEMPT test fix
Test: atest CallSequencingTests
Change-Id: I8ab0fb6b371bc5414124a9a4fd50a829b369479c