Removed the useless first key in schema cache

[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.

---

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

[sonarqubecloud]

Quality Gate passed

Issues
44 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
2.9% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 51.29534% with 94 lines in your changes missing coverage. Please review.
✅ Project coverage is 41.13%. Comparing base (d5c1834) to head (91b9012).
⚠️ Report is 1 commits behind head on dev/1.3.

Files with missing lines	Patch %	Lines
...lyze/cache/schema/dualkeycache/impl/CacheImpl.java	61.25%	31 Missing ⚠️
...yze/cache/schema/dualkeycache/impl/CacheEntry.java	42.85%	12 Missing ⚠️
.../db/protocol/thrift/impl/ClientRPCServiceImpl.java	0.00%	11 Missing ⚠️
...b/db/protocol/rest/v2/impl/RestApiServiceImpl.java	0.00%	10 Missing ⚠️
...ache/schema/dualkeycache/impl/CacheLinkedList.java	59.09%	9 Missing ⚠️
...e/schema/dualkeycache/impl/ICacheEntryManager.java	12.50%	7 Missing ⚠️
.../schema/dualkeycache/impl/CacheEntryGroupImpl.java	42.85%	4 Missing ⚠️
...e/plan/analyze/cache/schema/DeviceSchemaCache.java	66.66%	3 Missing ⚠️
...chema/dualkeycache/impl/FIFOCacheEntryManager.java	80.00%	3 Missing ⚠️
...ol/thrift/impl/DataNodeInternalRPCServiceImpl.java	0.00%	2 Missing ⚠️
... and 2 more

Additional details and impacted files

@@              Coverage Diff              @@
##             dev/1.3   #16881      +/-   ##
=============================================
+ Coverage      41.12%   41.13%   +0.01%     
  Complexity       198      198              
=============================================
  Files           3589     3592       +3     
  Lines         236042   235806     -236     
  Branches       28518    28471      -47     
=============================================
- Hits           97077    97005      -72     
+ Misses        138965   138801     -164     

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