Cherry-pick: Ensure edited scripts provided from the client with newline switches and no other changes get converted to "\n" (#22196)

[iansltx]

Merged to main in #22199.

git checkout minor-fleet-v4.57.0
git checkout -b 22196-cherry-pick
git cherry-pick ea2a9787338f780f7deb744c029c50d29dd6829d
git push -u origin 22196-cherry-pick

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Please upload report for BASE (minor-fleet-v4.57.0@0b5b129). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
ee/server/service/software_installers.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##             minor-fleet-v4.57.0   #22202   +/-   ##
======================================================
  Coverage                       ?   65.23%           
======================================================
  Files                          ?     1493           
  Lines                          ?   116968           
  Branches                       ?     3462           
======================================================
  Hits                           ?    76303           
  Misses                         ?    33551           
  Partials                       ?     7114           

Flag	Coverage Δ
backend	66.51% <0.00%> (?)

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.