[LoopCacheAnalysis][NFC] Add a test case for improved loop cache analysis cost calculation

Added a motivating test case for D123400 where the loopnest has a
suboptimal loop order j-i-k. After D123400 we ensure that the order
of loop cache analysis output is loop i-j-k, despite the suboptimal
order in the original loopnest.

Reviewed By: bmahjour, #loopoptwg

Differential Revision: https://reviews.llvm.org/D122776