[llvm] [LV] Run simplifyRecipes after addExplicitVectorLength (PR #200794)

[Luke Lau via llvm-commits]

lukel97 wrote:

> Is there a tangible benefit from this? Not sure if we should diverge when it comes to running generic transforms depending on whether we are vectorizing with EVL or not
> 
> My reading from [#199510 (comment)](https://github.com/llvm/llvm-project/pull/199510#discussion_r3302421297) was that the extra runs are not actually needed?

In that case then we should just stick the `splice.right(splice.left(poison, val, evl), poison, evl) -> val` combine into `optimizeMasksForEVL`, when we do get around to adding it. It won't ever trigger on any non-EVL tail folded VPlans

https://github.com/llvm/llvm-project/pull/200794