fix(vpc-v2): fixing default scope id (#31102)

### Issue # (if applicable)

Closes .

### Reason for this change

Fix current default scope ids for IPAM.

### Description of changes

Fix current default scope ids for IPAM..

### Description of how you validated changes

Integration test deployment

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: shikha372

packages/@aws-cdk/aws-ec2-alpha/lib/ipam.ts

@@ -415,6 +415,11 @@ class IpamScopeBase implements IIpamScopeBase {
     readonly scopeType?: IpamScopeType,
   ) {
     this.scopeType = IpamScopeType.DEFAULT;
+    if (!props.ipamScopeId) {
+      throw new Error('ipamScopeId is required');
+    } else {
+      this.scopeId = props.ipamScopeId;
+    }
   }
 
   /**

packages/@aws-cdk/aws-ec2-alpha/test/integ.subnet-v2.js.snapshot/aws-cdk-vpcv2-alpha-new.assets.json

@@ -15,7 +15,12 @@
    "Properties": {
     "AddressFamily": "ipv6",
     "AwsService": "ec2",
-    "IpamScopeId": "DefaultPublicScope",
+    "IpamScopeId": {
+     "Fn::GetAtt": [
+      "Ipam50346F82",
+      "PublicDefaultScopeId"
+     ]
+    },
     "Locale": "eu-west-2",
     "PublicIpSource": "amazon"
    }

packages/@aws-cdk/aws-ec2-alpha/test/integ.subnet-v2.js.snapshot/aws-cdk-vpcv2-alpha-new.template.json

@@ -11,7 +11,6 @@
 import * as vpc_v2 from '../lib/vpc-v2';
 import * as ec2 from 'aws-cdk-lib/aws-ec2';
 import { AddressFamily, AwsServiceName, IpCidr, Ipam, IpamPoolPublicIpSource, SubnetV2 } from '../lib';
-//import {  Ipv6Cidr } from '../lib';
 import { IntegTest } from '@aws-cdk/integ-tests-alpha';
 import * as cdk from 'aws-cdk-lib';
 import { SubnetType } from 'aws-cdk-lib/aws-ec2';

packages/@aws-cdk/aws-ec2-alpha/test/integ.subnet-v2.js.snapshot/cdk.out

@@ -14,7 +14,12 @@
    "Type": "AWS::EC2::IPAMPool",
    "Properties": {
     "AddressFamily": "ipv4",
-    "IpamScopeId": "DefaultPrivateScope",
+    "IpamScopeId": {
+     "Fn::GetAtt": [
+      "IpamTestIpam6C9298EF",
+      "PrivateDefaultScopeId"
+     ]
+    },
     "Locale": "eu-central-1",
     "ProvisionedCidrs": [
      {
@@ -28,7 +33,12 @@
    "Properties": {
     "AddressFamily": "ipv6",
     "AwsService": "ec2",
-    "IpamScopeId": "DefaultPublicScope",
+    "IpamScopeId": {
+     "Fn::GetAtt": [
+      "IpamTestIpam6C9298EF",
+      "PublicDefaultScopeId"
+     ]
+    },
     "Locale": "eu-central-1",
     "PublicIpSource": "amazon"
    }

packages/@aws-cdk/aws-ec2-alpha/test/integ.subnet-v2.js.snapshot/integ.json

@@ -92,7 +92,7 @@ new SubnetV2(stack, 'testsubnet', {
   subnetType: SubnetType.PRIVATE_ISOLATED,
 });
 
-//validate ipv6
+//Validate ipv6 IPAM
 new SubnetV2(stack, 'validateIpv6', {
   vpc,
   ipv4CidrBlock: new IpCidr('10.3.0.0/24'),