fix: Increase health check to 15 minutes

Deployments are currently flaky with the health check failing every so often
due to rate limiting from AWS.

Increase the health check grace period as a temporary solution
to hopefully increase the determinism of deployments.

cdk/lib/__snapshots__/prism.test.ts.snap

@@ -79,7 +79,7 @@ exports[`The PrismEc2App stack matches the snapshot 1`] = `
   "Resources": {
     "AutoScalingGroupPrismASG36691601": {
       "Properties": {
-        "HealthCheckGracePeriod": 500,
+        "HealthCheckGracePeriod": 900,
         "HealthCheckType": "ELB",
         "LaunchTemplate": {
           "LaunchTemplateId": {

cdk/lib/prism.ts

@@ -109,6 +109,6 @@ export class Prism extends GuStack {
 		// Similarly the pattern does not offer support for extending the default ASG grace period via props
 		const cfnAsg = pattern.autoScalingGroup.node
 			.defaultChild as CfnAutoScalingGroup;
-		cfnAsg.healthCheckGracePeriod = 500;
+		cfnAsg.healthCheckGracePeriod = Duration.minutes(15).toSeconds();
 	}
 }