Use a common quote to instead of check database type

[lunny]

`` will be converted to different database quote by xorm. So check database type is unnecessary.

[codecov-commenter]

Codecov Report

Merging #16817 (00721a4) into main (697213b) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main   #16817      +/-   ##
==========================================
- Coverage   45.47%   45.46%   -0.01%     
==========================================
  Files         762      762              
  Lines       85975    85969       -6     
==========================================
- Hits        39095    39090       -5     
- Misses      40563    40564       +1     
+ Partials     6317     6315       -2     

Impacted Files	Coverage Δ
models/user.go	54.55% <100.00%> (+0.14%)	⬆️
modules/charset/charset.go	71.71% <0.00%> (-2.03%)	⬇️
modules/queue/workerpool.go	53.81% <0.00%> (-1.91%)	⬇️
modules/log/event.go	60.64% <0.00%> (-1.86%)	⬇️
modules/log/file.go	73.60% <0.00%> (-1.61%)	⬇️
services/gitdiff/gitdiff.go	73.25% <0.00%> (-0.98%)	⬇️
models/repo_list.go	77.64% <0.00%> (-0.79%)	⬇️
services/pull/pull.go	42.19% <0.00%> (+0.40%)	⬆️
models/error.go	39.53% <0.00%> (+0.46%)	⬆️
models/notification.go	66.00% <0.00%> (+0.87%)	⬆️
... and 4 more

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