Fix Flaky test GetShuffleReportForMultiPartTest (#241)

### What changes were proposed in this pull request?
```
org.opentest4j.AssertionFailedError: expected: <0> but was: <-218>
	at org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
	at org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:150)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:145)
	at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:527)
	at org.apache.uniffle.test.GetShuffleReportForMultiPartTest.validateRequestCount(GetShuffleReportForMultiPartTest.java:198)
	at org.apache.uniffle.test.GetShuffleReportForMultiPartTest.runTest(GetShuffleReportForMultiPartTest.java:185)
	at org.apache.uniffle.test.SparkIntegrationTestBase.runSparkApp(SparkIntegrationTestBase.java:74)
	at org.apache.uniffle.test.SparkIntegrationTestBase.run(SparkIntegrationTestBase.java:59)
	at org.apache.uniffle.test.GetShuffleReportForMultiPartTest.resultCompareTest(GetShuffleReportForMultiPartTest.java:141)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at 
```

### Why are the changes needed?
Fix flaky test


### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
UT passed

Co-authored-by: leixianming <[email protected]>

integration-test/spark3/src/test/java/org/apache/uniffle/test/GetShuffleReportForMultiPartTest.java

@@ -182,17 +182,17 @@ public int compare(String o1, String o2) {
       int expectRequestNum = mockRssShuffleManager.getShuffleIdToPartitionNum().values().stream()
           .mapToInt(x -> x.get()).sum();
       // Validate getShuffleResultForMultiPart is correct before return result
-      validateRequestCount(expectRequestNum * replicateRead);
+      validateRequestCount(spark.sparkContext().applicationId(), expectRequestNum * replicateRead);
     }
     return map;
   }
 
-  public void validateRequestCount(int expectRequestNum) {
+  public void validateRequestCount(String appId, int expectRequestNum) {
     for (ShuffleServer shuffleServer : shuffleServers) {
       MockedShuffleServerGrpcService service = ((MockedGrpcServer) shuffleServer.getServer()).getService();
       Map<String, Map<Integer, AtomicInteger>> serviceRequestCount = service.getShuffleIdToPartitionRequest();
-      int requestNum = serviceRequestCount.entrySet().stream().flatMap(x -> x.getValue().values()
-           .stream()).mapToInt(AtomicInteger::get).sum();
+      int requestNum = serviceRequestCount.entrySet().stream().filter(x -> x.getKey().startsWith(appId))
+          .flatMap(x -> x.getValue().values().stream()).mapToInt(AtomicInteger::get).sum();
       expectRequestNum -= requestNum;
     }
     assertEquals(0, expectRequestNum);