[fix](job) fix StreamingInsertJob incorrectly counting canceled tasks (#61894)

## What problem does this PR solve?
Problem Summary:
- `StreamingInsertJob` does not support manual task cancellation
- `cancelAllTasks()` is only triggered internally when job is STOPPED or
PAUSED, meaning the task was interrupted passively
- Change `canceledTaskCount.incrementAndGet()` in `cancelAllTasks()`,
when task is running `canceledTaskCount` need incr

Author: JNSimba

fe/fe-core/src/main/java/org/apache/doris/job/extensions/insert/streaming/StreamingInsertJob.java

@@ -437,8 +437,15 @@ public void cancelAllTasks(boolean needWaitCancelComplete) throws JobException {
             if (runningStreamTask == null) {
                 return;
             }
+            // Check status before cancel: if the task was still active (RUNNING or PENDING),
+            // count it as canceled. If already in a terminal state (e.g. FAILED), it was
+            // already counted by onStreamTaskFail(), so skip to avoid double-counting.
+            boolean wasActive = TaskStatus.RUNNING.equals(runningStreamTask.getStatus())
+                    || TaskStatus.PENDING.equals(runningStreamTask.getStatus());
             runningStreamTask.cancel(needWaitCancelComplete);
-            canceledTaskCount.incrementAndGet();
+            if (wasActive) {
+                canceledTaskCount.incrementAndGet();
+            }
         } finally {
             lock.writeLock().unlock();
         }