Merge CRA2 webpack plugins

[mucsi96]

Issue: #5005

What I did

• Increased the test coverage for app/react/src/server/cra-config.js
• Merge webpack plugins in case of react-scripts > 2.1.0

@igor-dv Please review

[codecov]

Codecov Report

Merging #5126 into next will increase coverage by 0.31%.
The diff coverage is 80%.

@@            Coverage Diff             @@
##             next    #5126      +/-   ##
==========================================
+ Coverage   35.23%   35.55%   +0.31%     
==========================================
  Files         596      596              
  Lines        7401     7406       +5     
  Branches     1015     1011       -4     
==========================================
+ Hits         2608     2633      +25     
+ Misses       4285     4272      -13     
+ Partials      508      501       -7

Impacted Files	Coverage Δ
app/react/src/server/cra-config.js	87.5% <80%> (+40.44%)	⬆️

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[ndelangen]

LGTM what do you say @igor-dv ?

[mucsi96]

@ndelangen @Hypnosphi Do you have any idea why the Danger build fails?

[Hypnosphi]

@mucsi96 this #5126 (comment)

[mucsi96]

@Hypnosphi Can you remove one of the labels bug or maintenance. Now it's failing because of both them 🤣

Please choose only one of these labels: ["bug","maintenance"]

[Hypnosphi]

LOL

[mucsi96]

@ndelangen @Hypnosphi Can we merge this?

[igor-dv]

2 weeks late, but Yey 🔥