SystemRuleManager checkBbr algorithm may cause a incorrect judgement | SystemRuleManager的checkBbr拥塞检测可能出现误判

## Issue Description

Type: *feature request*

### Describe what feature you want
`SystemRuleManager.class` checkBbr algorithm may cause a incorrect judgement.
checkBbr() source code:
```java
public static void checkSystem(ResourceWrapper resourceWrapper, int count) throws BlockException {
.......
// load. BBR algorithm.
if (highestSystemLoadIsSet && getCurrentSystemAvgLoad() > highestSystemLoad) {
if (!checkBbr(currentThread)) {
throw new SystemBlockException(resourceWrapper.getName(), "load");
}
}
.......
}

private static boolean checkBbr(int currentThread) {
if (currentThread > 1 &&
currentThread > Constants.ENTRY_NODE.maxSuccessQps() * Constants.ENTRY_NODE.minRt() / 1000) {
return false;
}
return true;
}
```
In `currentThread > Constants.ENTRY_NODE.maxSuccessQps() * Constants.ENTRY_NODE.minRt() / 1000`,
We konw that ` Constants.ENTRY_NODE.maxSuccessQps() * Constants.ENTRY_NODE.minRt() / 1000` is equal to BDP(Bandwidth-Delay Product), but `currentThread` is the num of currnet threads, so they're not in the same unit.
So I assume `currentThread` is equal to `curThreadNum * 1000 / 1000`. That means RT of curThreads are set to 1second fixedly.
When the actual RT is bigger than 1s and BDP less than `currentThread` ,it will cause overload .

### Describe your initial design (if present)
I think it can use `Constants.ENTRY_NODE.avgRt()` instead of `1s` to improve it.
```java
if (currentThread > 1 &&
currentThread * Constants.ENTRY_NODE.avgRt() / 1000 >
Constants.ENTRY_NODE.maxSuccessQps() * Constants.ENTRY_NODE.minRt() / 1000) {
return false;
}
```
Am I on the right track?
If right, i'm willing to submit a PR.
Thank u

### Additional context

Add any other context or screenshots about the feature request here.

Start with SystemRuleManager.checkSystem() and its private checkBbr() method, then inspect Constants.ENTRY_NODE.maxSuccessQps(), minRt(), and avgRt(). Verify whether currentThread and the BDP expression use compatible units, and assess the proposed avgRt-based calculation. Done means the BBR overload judgment is corrected or the unit concern is resolved with supporting validation.

Written by the indexing model from the issue text.