KAFKA-14985: attempt to fix ConnectionQuotasTest.testListenerConnectionRateLimitWhenActualRateAboveLimit() test by bumping episilon to 8 from 7

[machi1990]

The test was observed to be failing with

ConnectionQuotasTest > testListenerConnectionRateLimitWhenActualRateAboveLimit() FAILED
    java.util.concurrent.ExecutionException: org.opentest4j.AssertionFailedError: Expected rate (30 +- 7), but got 37.47891810856393 (600 connections / 16.009 sec) ==> expected: <30.0> but was: <37.47891810856393>
        at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:205)
        at kafka.network.ConnectionQuotasTest.$anonfun$testListenerConnectionRateLimitWhenActualRateAboveLimit$3(ConnectionQuotasTest.scala:412)
        at scala.collection.immutable.List.foreach(List.scala:333)
        at kafka.network.ConnectionQuotasTest.testListenerConnectionRateLimitWhenActualRateAboveLimit(ConnectionQuotasTest.scala:412)        Caused by:
        org.opentest4j.AssertionFailedError: Expected rate (30 +- 7), but got 37.47891810856393 (600 connections / 16.009 sec) ==> expected: <30.0> but was: <37.47891810856393>
            at app//org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
            at app//org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
            at app//org.junit.jupiter.api.AssertEquals.failNotEqual(AssertEquals.java:197)
            at app//org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:86)
            at app//org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1021)
            at app//kafka.network.ConnectionQuotasTest.acceptConnectionsAndVerifyRate(ConnectionQuotasTest.scala:904)

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[machi1990]

@rajinisivaram @apovzner can you've a look once you've some time? Thanks

[divijvaidya]

@machi1990 I am afraid just changing the bound is not going to help. Please see open PR #12045 associated with this fix for details and let me know what you think about the root cause fix there.

[machi1990]

Thanks @divijvaidya thanks.
I'll close this PR in favor of #12045