Fix use of pika
After LBCORE-1772 the messaging to RabbitMQ started to fail because the installed version of pika contains an API change with respect to embedded (contrib) version.
Changes:
- change the use of the API to match that of
pika>=1.0.0
- remove the embedded pika
- change CI job to publish directly to PyPI (see LBCORE-1806)
To pick up the fix we have to update https://gitlab.cern.ch/lhcb-core/nightlies-jenkins-scripts and update periodic tests scripts to LBCORE-1772