build-and-provide-package: use $WORKSPACE/binaries/ for buildresult, remove files of previous runs and handle missing packages.
build-and-provide-package: use $WORKSPACE/binaries/ for buildresult, remove files of previous runs and handle missing packages.

${WORKSPACE}/binaries/: we want to separate sources and binaries
so we don't conflict with each other. Therefore put the files we
get from cowbuilder into ${WORKSPACE}/binaries/

remove files of previous runs: we get rid of source files from
previous runs, since Copy Artifact Plugin copies files but if
building fails we find multiple versions inside the workspace.
Since we might want to build older versions as well there is no
simple heuristic we could rely on, therefore get rid of old
files.

handle missing packages: When source package "foo" provides
binary packages "bar" and "baz" in version 0.23 but version 0.42
doesn't provide "baz" any longer, then the no-longer-present
binary package "baz" will stay in the archive since it's not
longer listed in 0.42. In case we even build an version older
than 0.23 providing baz then adding the package will fail at all.
Therefore we get rid of binary packages from the archive that are
no longer build by the current version.

mika/jenkins-debian-glue,mika/jenkins-debian-glue,jbfavre/jenkins-debian-glue,hetznerZA/jenkins-debian-glue,n054/jenkins-debian-glue,linuxmaniac/jenkins-debian-glue,linuxmaniac/jenkins-debian-glue,zeha/jenkins-debian-glue,vorlock/jenkins-debian-glue,cclausen/jenkins-debian-glue,hashar/jenkins-debian-glue,zeha/jenkins-debian-glue,webtrekk-kane/jenkins-debian-glue,webtrekk-kane/jenkins-debian-glue,hetznerZA/jenkins-debian-glue,jbfavre/jenkins-debian-glue,vorlock/jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,hashar/jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,cclausen/jenkins-debian-glue,n054/jenkins-debian-glue,bmiklautz/jenkins-debian-glue,kartikm/jenkins-debian-glue,wikimedia/operations-debs-jenkins-debian-glue,tonin/jenkins-debian-glue,tonin/jenkins-debian-glue,bmiklautz/jenkins-debian-glue,wikimedia/operations-debs-jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,kartikm/jenkins-debian-glue