[fix](load) fix broker load progress due to retry (#42959)

## Proposed changes

Currently, when retrying a broker load, it will use a different
`load_id` with the same `job_id`.
The `total_scan_nums` in progress is accumulated by `job_id`.
This will cause the `total_scan_nums` progress to be multiple of the
actual scan nums.

For example, suppose a 10 instance broker load gets retried:

```
initial (0/10) 0% -> retry (0/20) 0% -> finish (10/20) 50%
```

fe/fe-core/src/main/java/org/apache/doris/load/loadv2/LoadLoadingTask.java

@@ -20,6 +20,7 @@
 import org.apache.doris.analysis.BrokerDesc;
 import org.apache.doris.analysis.UserIdentity;
 import org.apache.doris.catalog.Database;
+import org.apache.doris.catalog.Env;
 import org.apache.doris.catalog.EnvFactory;
 import org.apache.doris.catalog.OlapTable;
 import org.apache.doris.common.Config;
@@ -217,6 +218,8 @@ public void updateRetryInfo() {
         UUID uuid = UUID.randomUUID();
         this.loadId = new TUniqueId(uuid.getMostSignificantBits(), uuid.getLeastSignificantBits());
         planner.updateLoadId(this.loadId);
+        // reset progress on each retry, otherwise the finished/total num will be incorrect
+        Env.getCurrentProgressManager().registerProgressSimple(String.valueOf(callback.getCallbackId()));
     }
 
     void settWorkloadGroups(List<TPipelineWorkloadGroup> tWorkloadGroups) {