close db when insert finished

[rhoninl]

What this PR does / why we need it:
close db when insert finished
Will this PR make the community happier?
yes
Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #713

How is this PR tested

• unit test
• e2e test
• other (please specify)

Special notes for your reviewer:
close db when insert finished
Release note:

[codecov]

Codecov Report

Patch coverage: 33.33% and project coverage change: -0.06% ⚠️

Comparison is base (5a19f6b) 55.16% compared to head (0394752) 55.10%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #714      +/-   ##
==========================================
- Coverage   55.16%   55.10%   -0.06%     
==========================================
  Files          23       23              
  Lines        2277     2283       +6     
==========================================
+ Hits         1256     1258       +2     
- Misses        907      911       +4     
  Partials      114      114              

Files Changed	Coverage Δ
pkg/telemetryservice/sql/mysql/mysql.go	64.28% <0.00%> (-3.22%)	⬇️
pkg/telemetryservice/sql/sqlserver/sqlserver.go	63.41% <0.00%> (-3.26%)	⬇️
pkg/telemetryservice/sql/tdengine/tdengine.go	76.31% <100.00%> (+1.31%)	⬆️

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[tomqin93]

@leepala added 1 comment

[tomqin93]

LGTM