improve handling of failures, both in tests and after-test cleanup, in TestHDFSIntegration.java

There are multiple issues making HDFS sync tests flaky or sometimes failing.

1. TestHDFSIntegrationBase.java should provide best-attempt cleanup in cleanAfterTest() method. Currently, if any cleanup operation fails, the rest of cleanup code is not executed. Cleanup logic would not normally fail if corresponding test succeeds. But if some do not, short-circuiting some cleanup logic tends to cascade secondary failures which complicate troubleshooting.

2. TestHDFSIntegration*.java classes do not guarantee calling close() method on Connection and Statement objects. It happens because
a) no try-finally or try-with-resource is used, so tests can skip close() calls if fail in the middle.
b) many methods re-open Connection and Statement multiple times, yet provide a single close() at the end.

3. Retry logic uses recursion in some places, as in startHiveServer2() and verifyOnAllSubDirs. Better to implement it via straightforward retry loop. Exception stack trace is more confusing than it needs to be in case of recursive calls. Plus, with NUM_RETRIES == 10, at least theoretically, it creates running out of stack as an unnecessary failure mechanism.

4. startHiveServer2() ignores hiveServer2.start() call failure, only logging info message.

5. Starting hiveServer2 and Hive metastore in separate threads and then keeping those threads alive seems unnecessary, since both servers' start() methods create servers running on their own threads anyway. It effectively leads to ignoring the start() method failure for both servers. Also, it leaves no guarantee that hiveServer2 will be started after the Hive metastore - both start from independent threads with no cross-thread coordination mechanism in place.

6. Thread.sleep() missing in multiple places between HiveServer2 SQL calls changing permissions and verifyOnAllSubDirs() calls verifying that those changes took effect.