fix(doc): optimze README.md and reference.conf comment

[317787106]

What does this PR do?

1. TronNetDelegate — wrap LockSupport.park() in a while (!hitDown && !Thread.currentThread().isInterrupted()) loop so that spurious unparks (e.g. from Thread.interrupt() in close()) cannot trigger the System.exit(0) path prematurely, and so the hit-thread exits cleanly when the Spring context is destroyed.

2. SolidityNode — fix a shutdown race in getBlockByNum(): when a gRPC exception is thrown while the node is shutting down (!flag || isHitDown()), break out immediately instead of sleeping exceptionSleepTime (1 s) and retrying.

3. ShieldedReceiveTest.pushSameSkAndScanAndSpend — fix a test isolation bug and a performance regression:

   • The test relied on the genesis bypass in validBlock() (latestBlockHeaderNumber == 0 → return true) to skip DPoS schedule validation. When prior tests cause the consensus background task to produce blocks, this bypass no longer applies and the block push fails with ValidateScheduleException.
   • Replace hardcoded System.currentTimeMillis() timestamps with nextScheduledTime(), which looks up the nearest slot where the witness is actually scheduled according to DposSlot.
   • Stop ConsensusService before manual block pushes: DposTask shares the same localwitness key and would race to produce blocks at the same slot, triggering switchFork and making the test slow.

4. reference.conf — remove the stale "Keys that cannot auto-bind" comment block; those implementation details belong in the source classes, not in the config template.

5. README.md — surface reference.conf alongside config.conf in the configuration-file list so users know a built-in defaults template exists (added in v4.8.2).

Why are these changes required?

• The single LockSupport.park() call could be woken by Thread.interrupt() from close(), causing the process to reach System.exit(0) before hitDown was ever set. With the while-loop fix, close() calling interrupt() caused a busy-spin because park() returns immediately when interrupted but the loop never exited — adding the isInterrupted() guard lets the thread exit cleanly.
• During shutdown, a transient gRPC exception in getBlockByNum() triggered a 1-second sleep and an unnecessary retry loop, delaying clean exit and producing noisy error logs.
• pushSameSkAndScanAndSpend passed in isolation because the chain started at genesis (block 0), bypassing DPoS validation. In a full test run, the consensus background task produces blocks before this test runs, advancing the head past 0 and exposing the missing schedule-aware timestamp logic.
• The reference.conf comment described internal normalisation details that have since been refactored into the Java classes.
• reference.conf was introduced in v4.8.2 but not mentioned in the README.

This PR has been tested by:

• Unit Tests
  • testGetBlockByNumNoErrorOnExceptionDuringShutdown: verifies the shutdown race fix — method breaks in < 500 ms; without the fix a 1-second sleep fires first.
  • pushSameSkAndScanAndSpend: now stable in both single-test and full-suite runs.
• Manual Testing

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