[Discussion] RandomLoadBalance optimize the same weight judgement

### Pre-check

- [X] I am sure that all the content I provide is in English.

### 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

Dubbo java 3.2, Open-JDK 1.8, Windows

### Steps to reproduce this issue

we judge if the weight is same after accumulation. It will cause us to do an additional addition operation. We can move the logic to determine if the weights are the same before accumulation. So we can reduce addition operation.

### What you expected to happen

We don't need to do an additional operation. It reduces performance

### 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)

Start by locating the Java SDK's RandomLoadBalance implementation and the tests covering its weight calculation; no specific file or test is named in the issue. Review the weight-equality check and accumulation path, then verify that the optimization avoids the extra addition while preserving load-balancing behavior.

Written by the indexing model from the issue text.