testsuite: Remove `buildbox-run` from testsuite-fedora:minimal image

Sam Thursfieldrequested to merge
sam/minimal-fix into master

BuildStream will now raise an error if buildbox-run is present but non functional. In this image, it is non-functional due to missing bwrap, so we need to correctly remove it.

This is required for https://github.com/apache/buildstream/pull/1746

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