Added database check for flush on local & Optimized the UTF-8 param in IT

[Caideyipi]

Description

As the title said.

---

This PR has:

• been self-reviewed.
  • concurrent read
  • concurrent write
  • concurrent read and write
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods.
• added or updated version, license, or notice information
• added comments explaining the "why" and the intent of the code wherever would not be obvious
  for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold
  for code coverage.
• added integration tests.
• been tested in a test IoTDB cluster.

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Key changed/added classes (or packages if there are too many classes) in this PR

[codecov]

Codecov Report

❌ Patch coverage is 0% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.73%. Comparing base (fd3726f) to head (55d6ca1).

Files with missing lines	Patch %	Lines
...g/apache/iotdb/db/storageengine/StorageEngine.java	0.00%	18 Missing ⚠️
.../service/thrift/ConfigNodeRPCServiceProcessor.java	0.00%	3 Missing ⚠️
...yengine/plan/relational/sql/parser/AstBuilder.java	0.00%	3 Missing ⚠️
...ol/thrift/impl/DataNodeInternalRPCServiceImpl.java	0.00%	1 Missing ⚠️
...ion/config/executor/ClusterConfigTaskExecutor.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17365      +/-   ##
============================================
+ Coverage     39.62%   39.73%   +0.11%     
  Complexity      312      312              
============================================
  Files          5127     5127              
  Lines        346203   346215      +12     
  Branches      44070    44073       +3     
============================================
+ Hits         137169   137584     +415     
+ Misses       209034   208631     -403     

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[sonarqubecloud]

Quality Gate failed

Failed conditions
5.4% Duplication on New Code (required ≤ 5%)

See analysis details on SonarQube Cloud