PayPal webhooks registering: fix concurrent registering issue

[andrii-kovalenko-ct]

Related to Automatic Types Sync: fix concurrent modification issue

If the service is run simultaneously on multiple nodes/environments, it is possible that it will try to register web hooks on the same PayPal Plus applications concurrently

Solution:

• [ ] investigate what happens if webhooks are registered twice for the same PayPal Plus application
• [ ] based on the result - create a solution how to prevent double registering of the webhooks