Allow the worker to start ffmpeg to encode the video

[Martchus]

See https://progress.opensuse.org/issues/68923#note-7

[codecov]

Codecov Report

Merging #3292 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3292      +/-   ##
==========================================
+ Coverage   91.51%   91.52%   +0.01%     
==========================================
  Files         215      215              
  Lines       13065    13065              
==========================================
+ Hits        11956    11958       +2     
+ Misses       1109     1107       -2     

Impacted Files	Coverage Δ
lib/OpenQA/WebAPI/Controller/Test.pm	96.58% <0.00%> (+0.56%)	⬆️

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