[LoopCacheAnalysis] Remove tryDelinearizeFixedSize (NFCI) (#177552)
LoopCacheAnalysis has its own function `tryDelinearizeFixedSize`, which
is a wrapper of Delinearization. Due to recent changes in
Delinearization, this function has become almost equivalent to
`delinearizeFixedSizeArray` and is no longer necessary. This patch
removes it.