chore(rds): add default engine version for aurora mysql version "3.04.2" (#30306)

### Issue # (if applicable)

Closes #30109 

### Reason for this change


Currently CDK does not show option to select the Engine version `3.04.2`


### Description of changes


Update the below class name to include "3.04.2"

```ts
export class AuroraMysqlEngineVersion {
public static readonly VER_3_04_2 = AuroraMysqlEngineVersion.builtIn_8_0('3.04.2');
}

```

### Description of how you validated changes


unit and integration tests

### 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)

Author: yasomaru

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

@@ -591,6 +591,8 @@ export class AuroraMysqlEngineVersion {
   public static readonly VER_3_04_0 = AuroraMysqlEngineVersion.builtIn_8_0('3.04.0');
   /** Version "8.0.mysql_aurora.3.04.1". */
   public static readonly VER_3_04_1 = AuroraMysqlEngineVersion.builtIn_8_0('3.04.1');
+  /** Version "8.0.mysql_aurora.3.04.2". */
+  public static readonly VER_3_04_2 = AuroraMysqlEngineVersion.builtIn_8_0('3.04.2');
   /**
    * Version "8.0.mysql_aurora.3.05.0"
    * @deprecated Aurora MySQL 8.0.mysql_aurora.3.05.0 is no longer supported by Amazon RDS.