[llvm] [RISCV][LoopVectorize] Use DataWithEVL as the preferred tail folding style (PR #148686)

[Luke Lau via llvm-commits]

lukel97 wrote:

This was reverted due to a crash in llvm-test-suite picked up by the clang-riscv-gauntlet buildbot. 

The crash was caused by `setTailFoldingStyles` not checking the legality of EVL tail folding whenever the tail style wasn't forced, i.e. returned by TTI.

I've fixed and relanded this in 20c52e423161d3a70d58caf6b0298094cb62e4e7

https://github.com/llvm/llvm-project/pull/148686