Remove PVCs during MajorVersion Upgrade if PostgreSQL has more than one instance

As I spoke on Slack with Matheo: https://stackgres.slack.com/archives/C014UGLAD9R/p1746621217138469

Problem is repreducible and straightforward:

1. Create PostgreSQL with 3 instances
2. Scale to 1 instance
3. Perform MajorVersion Upgrade
4. Scale back to 3 instances
5. Enjoy broken instances

The resolution is pretty simple - removing PVCs belonging to additional instances. Could You please add such funtionality to MajorVersionUpgrade process, so it detecs additional PVCs and cleans them up?