[LAA] Pass maximum stride to isSafeDependenceDistance. (#90036)

As discussed in https://github.com/llvm/llvm-project/pull/88039, support
different strides with isSafeDependenceDistance by passing the maximum
of both strides.

isSafeDependenceDistance tries to prove that
    |Dist| > BackedgeTakenCount * Step
holds. Chosing the maximum stride computes the maximum range accesed by
the loop for all strides.

PR: https://github.com/llvm/llvm-project/pull/90036