Testing zero-copy bugs fixes (not for merging)

[szetszwo]

This fix will be split into multiple JIRAs: RATIS-2164, RATIS-2151, RATIS-2173

The following are the bugs found so far:

1. LeakDetector: asserted allLeaks is non-empty but printed "allLeaks.size = 0"
   • Another bug: Tracks are added to the set before calling retain. Without calling retain at all, it is not a leak.
2. SimpleTracing and AdvancedTracing: the methods should be synchronized.
   • Minor presentation problem: AdvancedTracing should have a single track list instead of retainsTraces and releaseTraces.
3. GrpcClientProtocolService.UnorderedRequestStreamObserver.processClientRequest(..) should use try-finally.
4. GrpcLogAppender.appendLog(..) calls release() incorrectly for exception.
5. LogAppenderDefault.sendAppendEntriesWithRetries(..) calls release() incorrectly for exception.
6. LogSegment cache can release an entry multiple times.
7. LogSegment.loadCache(..) should call retain() for cache hit.
8. SegmentedRaftLog.retainLog(..): between getting the entry and calling retain(), the entry can be released. The "fail to retain" exception, if there is any, can be ignored since It is the same as a cache miss. See #1153
9. SegmentedRaftLog.retainEntryWithData(..) should release for exception.
10. Test bug: the log entries stored in SimpleStateMachine4Testing can be released.
11. LogSegment: New entries can be added after EntryCache is closed.
12. MemoryRaftLog has similar problems as in SegmentedRaftLog.
13. SegmentedRaftLogWorker should clean up unfinished tasks in the queue after stopped running.

[szetszwo]

Finally, it is able to pass all the tests (with a few retries). Note that there are probably some other zero copy bugs. Will fix them separately.

[szetszwo]

This can pass all the tests (with a few retries). Since this change is quite big (56kB) and non-trivial, I will split this to a few JIRAs:

1. The current JIRA RATIS-2164 for fixing LeakDetector. (I will leave this PR as-is and submit another PR.)
2. RATIS-2151 for fixing gRPC.
3. RATIS-2159 for fixing other non-gRPC cases.

I will see if (2) and (3) needed to be further split.

BTW, we should move LeakDetector enabling from MiniRaftClusterWithGrpc to MiniRaftCluster. It will be able to detect more failures.