Remove some printed errMsg when stop DN

[Wei-hao-Li]

Problem
During DataNode shutdown, an active query may be interrupted and transition to FAILED. Its resources can then be cleaned up concurrently through two paths:
Path 1: FragmentInstance state-change listener
→ Close drivers
→ Force-deregister the FI from the memory pool

Path 2: DriverScheduler abort
→ forceDeregisterFragmentInstance
→ SourceHandle.abort
→ MemoryPool.free
If Path 1 removes the FI memory registration firstly, it will throw MemoryLeakException because some PlanNode memory reservations are still non-zero.
Path 2 may subsequently attempt to release memory retained by a SourceHandle. Since the Query/FI registration has already been removed, MemoryPool.free() throws IllegalArgumentException:
RelatedMemoryReserved can't be null when freeing memory.

Fix
Checks isStopping before logging query cleanup errors in. And move setStopping before stop ExternalRPCService to ensure Stopping is set before query failed.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.85%. Comparing base (b94aa09) to head (2b01d11).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
.../execution/fragment/FragmentInstanceExecution.java	0.00%	4 Missing ⚠️
...ueryengine/execution/schedule/DriverScheduler.java	0.00%	4 Missing ⚠️
.../apache/iotdb/db/service/DataNodeShutdownHook.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18799      +/-   ##
============================================
+ Coverage     45.83%   45.85%   +0.01%     
  Complexity      712      712              
============================================
  Files          5498     5498              
  Lines        397501   397505       +4     
  Branches      51737    51741       +4     
============================================
+ Hits         182200   182278      +78     
+ Misses       215301   215227      -74     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.