ci: update Jenkinsfile.release to use multiflexi build images

Use multiflexi-<distroFamily>:<distroCode> Docker images instead of

multiflexi-<distroCode>:latest for builds with repo.multiflexi.eu.

Add workspace cleanup to prevent permission issues.

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: Vitexus

debian/Jenkinsfile.release

@@ -49,6 +49,7 @@ distributions.each { distro ->
                         sh 'dch -b -v ' + buildVer  + ' "' + env.BUILD_TAG  + '"'
                         sh 'sudo apt-get update --allow-releaseinfo-change'
                         sh 'sudo chown -R jenkins:jenkins . ..'
+                        sh 'sudo rm -rf debian/$(dpkg-parsechangelog --show-field Source)/ debian/.debhelper/ debian/tmp/'
                         sh 'debuild-pbuilder -r"sudo -E" -i -us -uc -b'
                         sh 'mkdir -p $WORKSPACE/dist/debian/ ; rm -rf $WORKSPACE/dist/debian/* ; for deb in $(cat debian/files | awk \'{print $1}\'); do mv "../$deb" $WORKSPACE/dist/debian/; done'
                         artifacts = sh (