Add regression test for libignition-gazebo4

[traversaro]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[traversaro]

Actually the error is the same for ign gazebo 5, i.e. :

export PREFIX=/home/conda/feedstock_root/build_artifacts/libignition-gazebo4_1625662076452/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeh
export SRC_DIR=/home/conda/feedstock_root/build_artifacts/libignition-gazebo4_1625662076452/test_tmp
Library error for [$PREFIX/lib/libignition-gazebo4-ign.so.4.9.1]: can't load $PREFIX/lib/libignition-gazebo4-ign.so.4.9.1
Tests failed for libignition-gazebo4-4.9.1-h370f392_0.tar.bz2 - moving package to /home/conda/feedstock_root/build_artifacts/broken
WARNING:conda_build.build:Tests failed for libignition-gazebo4-4.9.1-h370f392_0.tar.bz2 - moving package to /home/conda/feedstock_root/build_artifacts/broken
WARNING conda_build.build:tests_failed(2955): Tests failed for libignition-gazebo4-4.9.1-h370f392_0.tar.bz2 - moving package to /home/conda/feedstock_root/build_artifacts/broken
TESTS FAILED: libignition-gazebo4-4.9.1-h370f392_0.tar.bz2

Unfortunatly it is not trivial to debug due to the use of Ruby in the implementation of the ign command, probably it is worth to wait for gazebosim/gz-sim#694 that should provide pure C++ programs that may be easier to debug.

[diegoferigo]

I cross-post also here from the twin pr:

The segfault seems to me what I experienced and described in conda-forge/libignition-common-feedstock#36 (comment). After rebuilding libignition-gazebo5 locally with conda mambabuild, it stopped crashing.

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I'm not sure what could differ between using the libignition-gazebo5 package generated in CI and the locally generated package.