[Feature](broker-load) Add priority info for ShowLoadStmt. (#20984)

Following pr #20628 , add priority information of the load job.

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

@@ -793,7 +793,7 @@ public abstract class LoadJob extends AbstractTxnStateChangeCallback implements
 
             // task info
             jobInfo.add("cluster:" + getResourceName() + "; timeout(s):" + getTimeout()
-                    + "; max_filter_ratio:" + getMaxFilterRatio());
+                    + "; max_filter_ratio:" + getMaxFilterRatio() + "; priority:" + getPriority());
             // error msg
             if (failMsg == null) {
                 jobInfo.add(FeConstants.null_string);