enhance: remove duplicated data generation APIs for bulk insert test

[cydrain]

Issue: #22837

including following changes:

1. Add API CreateInsertData() and BuildArrayData() in internal/util/testutil
2. Remove duplicated test APIs from importutilv2 unittest and bulk insert integration test

[bigsheeper]

/lgtm

[mergify[bot]]

@cydrain ut workflow job failed, comment rerun ut can trigger the job again.

[bigsheeper]

/lgtm

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 96.17225% with 16 lines in your changes are missing coverage. Please review.

Project coverage is 82.01%. Comparing base (1e1fba0) to head (48616f9). Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #32889      +/-   ##
==========================================
+ Coverage   81.84%   82.01%   +0.16%     
==========================================
  Files        1006     1006              
  Lines      126941   127360     +419     
==========================================
+ Hits       103899   104450     +551     
+ Misses      19110    18936     -174     
- Partials     3932     3974      +42     

Files	Coverage Δ
internal/util/testutil/test_util.go	96.05% <96.17%> (+1.31%)	:arrow_up:

... and 25 files with indirect coverage changes

[cydrain]

/run-cpu-e2e

[mergify[bot]]

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[mergify[bot]]

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

[cydrain]

/run-cpu-e2e

[mergify[bot]]

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

[cydrain]

/run-cpu-e2e

[mergify[bot]]

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

[mergify[bot]]

@cydrain

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[cydrain]

/rerun ut

[bigsheeper]

/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia, cydrain

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