RFR (S) 8229416: Shenandoah: Demote or remove ShenandoahOptimize*Final optimizations

[Roman Kennke]

>>> The first optimization is eliminating barriers on constants, that are handled separately, and never>>> get exposed as from-space objects. We should keep that optimization
on, but to add future debugging,
>>> we would want to keep the flag as diagnostic.
>>
>> I believe this optimization actually does nothing (interesting). C2
>> already optimizes access to static-finals to inlined constants, and we
>> eliminate barriers on inlined constants. We might want to check & verify
>> this, but I strongly suspect this optimization is actually a no-op (at
>> least in most/all interesting cases).
> 
> Maybe?
> 
> It would rather keep current behavior as is, and treat this as the cleanup. We can remove
> ShenandoahOptimizeStaticFinals once we prove it is irrelevant.

Yes, go!

Thanks,
Roman