bilby_pipe: download and run full test suite

This MR adds a new bilby_pipe-tests.sh script that downloads and runs the full test suite for bilby_pipe.

This should expose the failures noted in https://git.ligo.org/computing/helpdesk/-/issues/2885#note_608071.

Currently this requires downloading the 'raw' tarball from gitlab, however Distribute tests/ directory in tarball (lscsoft/bilby_pipe!487 - merged) should enable us to download the PyPI tarball instead (as per lscsoft-glue-tests.sh, for example).