[Security/Safety] Use privileged dnfdaemon-system only where necessary

[genodeftest]

Currently, dnfdaemon-system is started when yumex-dnf starts and is used for all operations involving dnf such as getting any package list or metadata or search. dnfdaemon-system is running as root and as such is a potential risk of security bugs.

I'd expect yumex-dnf to run without its root backend for most situations.

The only situations where root privileges are required are

• running the real package transaction
• history access (this might depend on system umask. Can someone please confirm they can run dnf history info last and dnf history list as ordinary user?)

[timlau]

It is a mess to switch between system & session API, metadata has to be loaded twice, memory usage will be much higher etc