This addresses ENG-9451, which was caused by D13404.
Before that diff, we would only match a pending thread ID to a realized thread if the thread type matched.
In that diff, we wanted to relax this condition a little bit so that a pending thick thread would match a realized thin thread, and vice versa.
However, we didn't consider a scenario where somebody creates a LOCAL thread and then somebody else leaves. In this case, the use of pendingThreadType(actualMemberIDs.length - 1, thickOrThin) would return a different thread type than the current thread's.
This diff replaces the usage of pendingThreadType, and brings back the old behavior of checking the realized thread type. However, we make sure to include both thin and thick thread types for each realized thread.
Depends on D13553