feat: graduate prebuilds to general availability (#18607)

This PR removes the prebuilds experiment and allows the use of prebuilds
without opting into an experiment.

site/src/api/typesGenerated.ts

@@ -795,7 +795,6 @@ export type Experiment =
 	| "example"
 	| "notifications"
 	| "web-push"
-	| "workspace-prebuilds"
 	| "workspace-usage";
 
 export const Experiments: Experiment[] = [
@@ -803,7 +802,6 @@ export const Experiments: Experiment[] = [
 	"example",
 	"notifications",
 	"web-push",
-	"workspace-prebuilds",
 	"workspace-usage",
 ];