docker/jetty - removes javax.mail library provided by the docker imag…

[pmauduit]

…e (georchestra/georchestra#4233)

geOrchestra/geonetwork checklist

• PR only involves cherry-picked commits from upstream.
• PR contains custom code which will soon be available in an upstream release and can be overriden => mention core-geonetwork version if possible.
• PR contains custom geOrchestra code, which need to be verified during future migrations.
  • I have properly filled the migration-helper-changelog.md file.

[pmauduit]

Same as previous (could not manage to use the automatic backport feature, because of the modification on the PR template which does not exist in this branch).