Remove old pax files after upgrade

[AnthonyGiorgio]

When performing a zopen upgrade, the very last step should be to prune pax files that are older than the currently installed version. The current behavior keeps all packages around, and will eventually chew up all the disk space. Keeping a single package around will keep the overall disk space relatively stable across upgrades.

[IgorTodorovskiIBM]

We may want to enhance zopen-clean -c https://github.com/ZOSOpenTools/meta/blob/main/bin/zopen-clean#L30 as well to clear the cachefor a particular package and also to specify the # of cache files to keep for a particular package (sorted by date).

A global setting for this would also be good