Remove field check logic for upsert

[congqixia]

Previously go sdk removed field check for insert but same logic remains in Upsert method
See also #613
/kind bug

[sre-ci-robot]

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[yah01]

/lgtm

[codecov]

Codecov Report

Merging #617 (ebd17cd) into master (94c4107) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #617      +/-   ##
==========================================
- Coverage   75.19%   75.14%   -0.05%     
==========================================
  Files          41       41              
  Lines        4056     4032      -24     
==========================================
- Hits         3050     3030      -20     
+ Misses        893      890       -3     
+ Partials      113      112       -1     

Files	Coverage Δ
client/insert.go	79.92% <100.00%> (-0.27%)	⬇️