BlockCacheTest is flaky

[lizhanhui]

[ERROR] Tests run: 5, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.932 s <<< FAILURE! -- in com.automq.stream.s3.cache.BlockCacheTest [ERROR] com.automq.stream.s3.cache.BlockCacheTest.testGenReadahead -- Time elapsed: 0.905 s <<< FAILURE! org.opentest4j.AssertionFailedError: expected: <69206016> but was: <33554432> at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151) at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132) at org.junit.jupiter.api.AssertEquals.failNotEqual(AssertEquals.java:197) 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 com.automq.stream.s3.cache.BlockCacheTest.testGenReadahead(BlockCacheTest.java:140) at java.base/java.lang.reflect.Method.invoke(Method.java:578) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)