Avoid unnecessary encoding of slashes in URIs in RestControllerTest

[osma]

Reasons for creating this PR

In #1282, I reformatted JSON strings. But the JSON reformatting tool I used also escapes regular slashes, which appear a lot in URIs. I didn't notice that before merging 😔 So I'm removing the unnecessary escapes in this PR.

Link to relevant issue(s), if any

• Followup fix to PR Reformat remaining JSON strings in RestControllerTest to avoid long lines #1282

Description of the changes in this PR

Remove unnecessary backslashes in JSON strings within RestControllerTest

Known problems or uncertainties in this PR

n/a

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if not, explain why below)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #1283 (7040175) into master (9dc7ea9) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1283   +/-   ##
=========================================
  Coverage     69.36%   69.36%           
  Complexity     1649     1649           
=========================================
  Files            32       32           
  Lines          4047     4047           
=========================================
  Hits           2807     2807           
  Misses         1240     1240           

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