RFR: 8321122: Shenandoah: Remove ShenandoahLoopOptsAfterExpansion flag

[Roman Kennke]

On Thu, 30 Nov 2023 16:00:17 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> More flags cleanup. `ShenandoahLoopOptsAfterExpansion` was added long time ago to gate more aggressive barrier optimizations in C2. It was default since then. There seem to be no reason to keep it as the flag. Just checking, @rwestrel -- you don't need it anymore, right?
> 
> Additional testing:
>  - [x] `hotspot_gc_shenandoah`

Seems ok to remove the flag, but not sure if the optimization pass is still useful at all? It might be a left-over from pre-LRB and not do anything useful? (I don't know that, I haven't checked, but it could be)

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Marked as reviewed by rkennke (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16908#pullrequestreview-1768547290