[LV][NFC]Preselect folding style while chosing the max VF, NFC.

Selects the tail-folding style while choosing the max vector
factor and storing it in the data member rather than calculating it each
time upon getTailFoldingStyle call.

Part of https://github.com/llvm/llvm-project/pull/76172

Reviewers: ayalz, fhahn

Reviewed By: fhahn

Pull Request: https://github.com/llvm/llvm-project/pull/81885