Build-Failure in test for CSVReadFunctionTest

### Expected behavior

The tests should run without failure.

### Actual behavior

In run https://ci-builds.apache.org/job/JMeter/job/JMeter%20s390x/261/console we get an assertion error.

```
FAILURE 2.0sec, org.apache.jmeter.functions.CSVReadFunctionTest > concurrentRequestsToSameCsv()
org.opentest4j.AssertionFailedError: expected: but was:
at app//org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:158)
at app//org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:139)
at app//org.junit.jupiter.api.AssertEquals.failNotEqual(AssertEquals.java:201)
at app//org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:184)
at app//org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:179)
at app//org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1188)
at app//org.apache.jmeter.functions.CSVReadFunctionTest.eq(CSVReadFunctionTest.java:62)
Suppressed: java.lang.RuntimeException: thread2
at org.apache.jmeter.functions.Synchronizer.failure(Synchronizer.java:41)
at org.apache.jmeter.functions.CSVReadFunctionTest.lambda$concurrentRequestsToSameCsv$0(CSVReadFunctionTest.java:92)
```

### Steps to reproduce the problem

Not sure yet, maybe you need the machine (an s390x), or run the test many times. Seems to be a flaky test, as it is not always reported.

### JMeter Version

main branch

### Java Version

_No response_

### OS Version

_No response_