Simplify and fix GetApprovalCounts

[6543]

close #11056

simple code can make things easy understandable and creat less issues

thanks to @CirnoT for helping me finding the related code

[codecov-io]

Codecov Report

Merging #11086 into master will increase coverage by 0.07%.
The diff coverage is 36.53%.

@@            Coverage Diff             @@
##           master   #11086      +/-   ##
==========================================
+ Coverage   43.46%   43.54%   +0.07%     
==========================================
  Files         597      598       +1     
  Lines       84706    84798      +92     
==========================================
+ Hits        36821    36922     +101     
+ Misses      43344    43331      -13     
- Partials     4541     4545       +4     

Impacted Files	Coverage Δ
models/issue_comment.go	46.68% <ø> (ø)
models/migrations/migrations.go	3.50% <ø> (ø)
models/migrations/v136.go	0.00% <0.00%> (ø)
models/repo_language_stats.go	66.37% <ø> (ø)
modules/analyze/code_langauge.go	81.25% <ø> (ø)
modules/auth/sso/basic.go	50.81% <0.00%> (+7.15%)	⬆️
modules/git/repo_language_stats.go	66.17% <ø> (ø)
modules/indexer/code/bleve.go	64.70% <ø> (ø)
routers/api/v1/user/watch.go	0.00% <0.00%> (ø)
routers/repo/http.go	42.60% <0.00%> (+1.27%)	⬆️
... and 22 more

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