Update insider target percentage to 50 in experiment configurations (microsoft#257133)

Author: bhavyaus

src/vs/workbench/services/coreExperimentation/common/coreExperimentationService.ts

@@ -64,7 +64,7 @@ const EXPERIMENT_CONFIGURATIONS: Record<string, ExperimentConfiguration> = {
 	},
 	insider: {
 		experimentName: STARTUP_EXPERIMENT_NAME,
-		targetPercentage: 20,
+		targetPercentage: 50,
 		groups: [
 			// Bump the iteration each time we change group allocations
 			{ name: StartupExperimentGroup.Control, min: 0.0, max: 0.25, iteration: 1 },