Fix #7869: Rename vgroup_table.cluster to cluster_name

[Gitkbc]

What this PR does:

• Fixes Oracle SQL failures caused by reserved keyword cluster
• Renames vgroup_table.cluster to cluster_name across all supported databases
• Updates MappingDO, DAO queries, and result mappings
• Adds database upgrade scripts to preserve existing data

Why this approach:

• Avoids vendor-specific quoting
• Prevents Oracle case-sensitivity issues
• Keeps schema consistent across database vendors

Backward compatibility:

• Existing installations are supported via upgrade scripts

Fixes #7869

[codecov]

Codecov Report

❌ Patch coverage is 41.66667% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.59%. Comparing base (5e5979b) to head (806b205).
⚠️ Report is 2 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...ver/storage/db/store/VGroupMappingDataBaseDAO.java	0.00%	5 Missing ⚠️
...ge/db/store/DataBaseVGroupMappingStoreManager.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #7925      +/-   ##
============================================
+ Coverage     71.58%   71.59%   +0.01%     
  Complexity      883      883              
============================================
  Files          1294     1294              
  Lines         49554    49555       +1     
  Branches       5884     5885       +1     
============================================
+ Hits          35475    35481       +6     
+ Misses        11159    11158       -1     
+ Partials       2920     2916       -4     

Files with missing lines	Coverage Δ
...in/java/org/apache/seata/core/store/MappingDO.java	100.00% <100.00%> (ø)
...ata/server/controller/VGroupMappingController.java	95.45% <100.00%> (ø)
...ge/redis/store/RedisVGroupMappingStoreManager.java	71.87% <100.00%> (ø)
...ge/db/store/DataBaseVGroupMappingStoreManager.java	5.55% <0.00%> (-0.33%)	⬇️
...ver/storage/db/store/VGroupMappingDataBaseDAO.java	0.00% <0.00%> (ø)

... and 6 files with indirect coverage changes

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[Gitkbc]

Hi maintainers,

I’ve addressed the SQL rename across all supported databases, added upgrade scripts, and included tests to improve coverage.

License and Spotless checks are now passing locally.
Please let me know if any additional adjustments or test coverage are required.

Thanks for your review.

[funky-eyes]

If we rename the column cluster to cluster_name,
what should we do with the existing vgroup data that has already been migrated to NamingServer for transaction group management?
How should the migration process to the new table structure be handled?