Fix code block when drafting release notes

The automation release pipeline, check-release-date, is drafting the release notes for the upcoming version by extracting release note summary and release note description from Jira tickets, and push the result to the doc.nuxeo.com-content repository.

During the extraction, the code block, small or long form, present in the tickets are not successfully extracted, they are removed from the final result.

We want to fix that, the code block should be present in the final result in the markdown format.

For example, such description:

Add a nuxeo.conf property nuxeo.mock.configuration has been added.

results in:

Add a nuxeo.conf property has been added.