change bloom dendro core delay to 20f

Based off these videos, the dendro core is counted as a gadget starting
at ~20f from the bloom reaction trigger. This is also the time when the
5 dendro core limit is checked. The delay on damage is likely caused by
the 12f linger of the core after being ruptured, hyperbloomed, or
burgeoned.

The spawn delay is probably not always 20f. My hypothesis is that it is
variable depending on the spawn location of the gadget. However for the
sim, 20f suffices.

https://discord.com/channels/845087716541595668/869210750596554772/1027611051124064356

pkg/reactable/bloom.go

@@ -10,7 +10,7 @@ import (
 	"github.com/genshinsim/gcsim/pkg/gadget"
 )
 
-const DendroCoreDelay = 45
+const DendroCoreDelay = 20
 
 func (r *Reactable) tryBloom(a *combat.AttackEvent) {
 	//can be hydro bloom, dendro bloom, or quicken bloom