[skip-changelog] Fix upload test according to CLI output refactoring

[MatteoPologruto]

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• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
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What kind of change does this PR introduce?

Code imperfection fix

What is the current behavior?

TestUploadWithInputDirContainingMultipleBinaries fails because the error output was slightly changed in PR #2003 and no longer contains the message Error during upload.

What is the new behavior?

The test works correctly:

PS C:\Users\m.pologruto\Desktop\Arduino\arduino-cli> go test github.com/arduino/arduino-cli/internal/integrationtest/upload -run TestUploadWithInputDirContainingMultipleBinaries
ok      github.com/arduino/arduino-cli/internal/integrationtest/upload  41.566s

Does this PR introduce a breaking change, and is titled accordingly?

No

Other information

No

[codecov]

Codecov Report

Base: 36.67% // Head: 36.68% // Increases project coverage by +0.01% 🎉

Coverage data is based on head (d5275a4) compared to base (cc24197).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2067      +/-   ##
==========================================
+ Coverage   36.67%   36.68%   +0.01%     
==========================================
  Files         228      228              
  Lines       19383    19383              
==========================================
+ Hits         7108     7111       +3     
+ Misses      11442    11440       -2     
+ Partials      833      832       -1     

Flag	Coverage Δ
unit	36.68% <ø> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
commands/lib/search.go	92.10% <0.00%> (+3.94%)	⬆️

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