chore(save-event): remove highcpu percentage option (#57535)

The feature is fully rolled out. The option is no longer needed. 

Depends on https://github.com/getsentry/sentry/pull/57534

src/sentry/options/defaults.py

@@ -748,13 +748,6 @@ register(
 register(
     "store.save-event-highcpu-platforms", type=Sequence, default=[], flags=FLAG_AUTOMATOR_MODIFIABLE
 )
-# For platform belongs to store.save-event-highcpu-platforms option, we want to reroute
-# events to highcpu dedicated queue. During rollout, I would like to have an option to control
-# the percentage of traffic to route to highcpu dedicated queue, so I can route
-# small amount of traffic to new highcpu worker pool, and observe the worker throughput
-# to adjust autoscaling. Once we verify the deployment, we can remove the usage for this
-# option.
-register("store.save-event-highcpu-percentage", default=0.0, flags=FLAG_AUTOMATOR_MODIFIABLE)
 register(
     "store.symbolicate-event-lpq-never", type=Sequence, default=[], flags=FLAG_AUTOMATOR_MODIFIABLE
 )