[llvm] [LV] Bundle partial reductions inside VPExpressionRecipe (PR #147302)

[Sam Tebbs via llvm-commits]

SamTebbs33 wrote:

> Ping. The test failure is maxbandwidth-regpressure.ll which needs adjusting since the register pressure of partial reductions has been reduced.

Done.

https://github.com/llvm/llvm-project/pull/147302