[Bug] Registry check does not work in the case of multiple registrations and subscriptions at the application level, and provider export error causes Dubbo to fail to start

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### Search before asking

- [X] I had searched in the [issues](https://github.com/apache/dubbo/issues?q=is%3Aissue) and found no similar issues.

### Apache Dubbo Component

Java SDK (apache/dubbo)

### Dubbo Version

dubbo3.2.16;
jdk openjdk21

### Steps to reproduce this issue

Dubbo3.2.16 uses two Nacos clusters as registration centers to implement application level multi subscription and multi subscription, and configure regirty.check=false. When one of the Nacos clusters is unavailable, dubbo serviceConfig. export reports an error causing startup failure, with the error message 'this.registry is null'

### What you expected to happen

When a Nacos cluster is unavailable, it should be possible to export services normally on another Nacos cluster and ignore the other Nacos cluster

### Anything else

_No response_

### Are you willing to submit a pull request to fix on your own?

- [x] Yes I am willing to submit a pull request on my own!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

Reproduce the failure with Dubbo 3.2.16, JDK 21, two Nacos clusters, and registry.check=false. Start at the serviceConfig.export path and the “this.registry is null” error; done means service export succeeds through the available cluster when the other cluster is unavailable.

Written by the indexing model from the issue text.