enhance: Add max file num limit and max file size limit for import (#31497)

[bigsheeper]

The max number of import files per request should not exceed 1024 by default (configurable).
The import file size allowed for importing should not exceed 16GB by default (configurable).

issue: #28521

pr: #31497

[bigsheeper]

rerun ut

[codecov]

Codecov Report

Attention: Patch coverage is 67.74194% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 80.79%. Comparing base (9977454) to head (37a50f8).
Report is 4 commits behind head on 2.4.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #31542      +/-   ##
==========================================
- Coverage   80.89%   80.79%   -0.11%     
==========================================
  Files         980      965      -15     
  Lines      143575   136584    -6991     
==========================================
- Hits       116150   110352    -5798     
+ Misses      23540    22519    -1021     
+ Partials     3885     3713     -172     

Files	Coverage Δ
pkg/util/paramtable/component_param.go	98.35% <100.00%> (-0.03%)	⬇️
internal/datanode/importv2/util.go	63.12% <16.66%> (-1.62%)	⬇️
internal/proxy/impl.go	86.18% <0.00%> (-0.20%)	⬇️

... and 39 files with indirect coverage changes

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bigsheeper, czs007

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• configs/OWNERS [czs007]
• internal/datanode/OWNERS [czs007]
• internal/proxy/OWNERS [czs007]
• pkg/util/OWNERS [czs007]

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