Revert "[AArch64] Set maximum VF with shouldMaximizeVectorBandwidth"

This reverts commit 64b6192e.

This broke LLVM AArch64 buildbot clang-aarch64-sve-vls-2stage:

https://lab.llvm.org/buildbot/#/builders/176/builds/1515

llvm-tblgen crashes after applying this patch.