[analyzer] Remove the redundant check about same state transition in `ArrayBoundCheckerV2.cpp`.

Summary: Since the `addTransitionImpl()` has a check about same state transition, there is no need to check it in `ArrayBoundCheckerV2.cpp`.

Reviewers: NoQ, xazax.hun, george.karpenkov

Reviewed By: NoQ

Subscribers: szepet, rnkovacs, a.sidorin, cfe-commits, MTC

Differential Revision: https://reviews.llvm.org/D47451

llvm-svn: 333531