dnf5 CLI: Redownload update for --offline switch

[mcrha]

This is with dnf5-5.2.4.0-20240715005730.21.g9c2e2150.fc41.x86_64

Steps, commands run as root:

1. dnf update and let it download the packages; then cancel the update
2. run again dnf update and notice the packages are not downloaded, they are recognized as being locally stored; cancel the update
3. run dnf update --offline - this time the packages are downloaded again, even they are stored locally, as verified in the previous step

I had a Fedora rawhide update, which meant to download 3GB of the data (according to the dnf message). Downloading it twice is a waste of bandwidth, time and the disk space (I fight with the disk space constantly, because this virtual machine has only ~20GB disk, thus I cannot even store those 3GB twice locally). The package cache should be shared for the --offline and not --offline variant of the update.

[jan-kolarik]

The data from dnf update and dnf update --offline are stored at different locations. But you're right that it would be a good optimization.