fix(release): ensure we release split package uploads as one batch

Use a central location in common.sh to define the default rsync options. Switch to use batched uploads by targeting a partial directory which is not taken into account by db update. Instead, once all packages that belong to a split package group are uploaded into the .partial directory, all artifacts are moved in one batch into the staging directory of the repo server. This reduced the window of opportunity for a partial release significantly to a tiny window.

Component: pkgctl release