storager: Fix QingStor error not handled as intended

[Prnyself]

No description provided.

[Prnyself]

As comment in #118 mentioned, I fixed the formatError func to handle Qingstor error as intended.

[Xuanwo]

Here is an overview of what got changed by this pull request:

Clones removed
==============
+ services/qingstor/storager.go  -1
         

See the complete overview on Codacy

[codecov]

Codecov Report

Merging #135 into master will increase coverage by 0.42%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
+ Coverage   84.72%   85.15%   +0.42%     
==========================================
  Files          12       12              
  Lines         943      943              
==========================================
+ Hits          799      803       +4     
+ Misses         90       87       -3     
+ Partials       54       53       -1

Impacted Files	Coverage Δ
services/qingstor/storager.go	82% <100%> (+0.58%)	⬆️
services/qingstor/utils.go	78.94% <0%> (+2.63%)	⬆️

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