fix: store wrong offset when build tantivy in nullable field

[smellthemoon]

#40454

[mergify]

@smellthemoon Please associate the related issue to the body of your Pull Request. (eg. “issue: #”)

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 80.51%. Comparing base (a56b240) to head (2a0fcf8).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/core/src/index/InvertedIndexTantivy.cpp	33.33%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #40452       +/-   ##
===========================================
+ Coverage   70.04%   80.51%   +10.46%     
===========================================
  Files         309     1474     +1165     
  Lines       27725   207394   +179669     
===========================================
+ Hits        19421   166976   +147555     
- Misses       8304    34346    +26042     
- Partials        0     6072     +6072     

Components	Coverage Δ
Client	79.69% <ø> (∅)
Core	70.03% <33.33%> (-0.02%)	⬇️
Go	82.25% <ø> (∅)

Files with missing lines	Coverage Δ
internal/core/src/index/InvertedIndexTantivy.cpp	87.02% <33.33%> (ø)

... and 1166 files with indirect coverage changes

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[mergify]

@smellthemoon E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[smellthemoon]

/run-cpu-e2e

[xiaofan-luan]

/lgtm
/approve

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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