fix(rds): monitoringInterval in DatabaseClusterProps does not work with token (#33516)

### Issue # (if applicable)

Closes #33504.

### Reason for this change

`monitoringInterval` prop in `DatabaseClusterProps` should accept a token.

### Description of changes

Skip validations if `monitoringInterval` is a token.

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

Added a unit test.

### 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: Tietew

packages/aws-cdk-lib/aws-rds/lib/cluster.ts

@@ -889,7 +889,10 @@ abstract class DatabaseClusterNew extends DatabaseClusterBase {
     if (props.enableClusterLevelEnhancedMonitoring && !props.monitoringInterval) {
       throw new ValidationError('`monitoringInterval` must be set when `enableClusterLevelEnhancedMonitoring` is true.', this);
     }
-    if (props.monitoringInterval && [0, 1, 5, 10, 15, 30, 60].indexOf(props.monitoringInterval.toSeconds()) === -1) {
+    if (
+      props.monitoringInterval && !props.monitoringInterval.isUnresolved() &&
+      [0, 1, 5, 10, 15, 30, 60].indexOf(props.monitoringInterval.toSeconds()) === -1
+    ) {
       throw new ValidationError(`'monitoringInterval' must be one of 0, 1, 5, 10, 15, 30, or 60 seconds, got: ${props.monitoringInterval.toSeconds()} seconds.`, this);
     }
 

packages/aws-cdk-lib/aws-rds/test/cluster.test.ts

@@ -3147,6 +3147,31 @@ describe('cluster', () => {
         });
       }).toThrow(`'monitoringInterval' must be one of 0, 1, 5, 10, 15, 30, or 60 seconds, got: ${monitoringInterval.toSeconds()} seconds.`);
     });
+
+    test('accept token for monitoring interval', () => {
+      // GIVEN
+      const stack = testStack();
+      const vpc = new ec2.Vpc(stack, 'VPC');
+      const parameter = new cdk.CfnParameter(stack, 'MonitoringIntervalParameter', { type: 'Number' });
+
+      // WHEN
+      new DatabaseCluster(stack, 'Database', {
+        engine: DatabaseClusterEngine.auroraMysql({ version: AuroraMysqlEngineVersion.VER_3_07_1 }),
+        credentials: {
+          username: 'admin',
+          password: cdk.SecretValue.unsafePlainText('tooshort'),
+        },
+        vpc,
+        writer: ClusterInstance.serverlessV2('writer'),
+        monitoringInterval: cdk.Duration.seconds(parameter.valueAsNumber),
+        enableClusterLevelEnhancedMonitoring: true,
+      });
+
+      // THEN
+      Template.fromStack(stack).hasResourceProperties('AWS::RDS::DBCluster', {
+        MonitoringInterval: { Ref: 'MonitoringIntervalParameter' },
+      });
+    });
   });
 
   test('addRotationSingleUser()', () => {