[NFC] Add CHECK lines for unordered FP reductions

An additional RUN line has been added to both strict-fadd.ll &
scalable-strict-fadd.ll to ensure the correct behaviour of these
tests where `-enable-strict-reductions` is false.

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D103015

Author: kmclaughlin-arm