[IndVarSimplify][NFC] Removed mayThrow from if-condition in predicateLoopExits of IndVarSimplify

Instruction has mayHaveSideEffects method that returns true if mayThrow return true because this is called internally in the first method.  As such, the call being removed is redundant.

Patch By: vdsered (Daniil Seredkin)
Differential Revision: https://reviews.llvm.org/D101685