Update VisualizerTask tests

[jawira]

Update tests for VisualizerTask:

• File extension must be the same as declared in format property.

<visualizer forma="svg" destination="build"/>      <!-- build.svg -->
<visualizer forma="svg" destination="build.svg"/>  <!-- build.svg -->
<visualizer forma="svg" destination="build.png"/>  <!-- build.png.svg -->

[codecov]

Codecov Report

Merging #1676 (2f66659) into main (453bfa2) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #1676   +/-   ##
=========================================
  Coverage     58.34%   58.34%           
  Complexity     6962     6962           
=========================================
  Files           355      355           
  Lines         16611    16611           
=========================================
  Hits           9692     9692           
  Misses         6919     6919           

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