enhance: Support varchar autoid for bulkinsertV1 (#30896)

[bigsheeper]

This PR is a supplement to PR #30377.

pr: #30896

[czs007]

/approve
/lgtm

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.20%. Comparing base (df16bf6) to head (001d299).
Report is 3 commits behind head on 2.3.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.3   #30913      +/-   ##
==========================================
+ Coverage   82.19%   82.20%   +0.01%     
==========================================
  Files         841      841              
  Lines      121457   121455       -2     
==========================================
+ Hits        99826    99842      +16     
+ Misses      18402    18381      -21     
- Partials     3229     3232       +3     

Files	Coverage Δ
internal/util/importutil/json_handler.go	90.54% <100.00%> (ø)

... and 15 files with indirect coverage changes