Change allow_vendor_change default to false with descriptive hint

[fhbash]

• Change the default value of allow_vendor_change from true to false so packages stick to their original vendor during upgrades (Use sticky vendors by default #712)
• When the solver blocks an update due to a vendor change restriction, print a hint suggesting --setopt=allow_vendor_change=true (Add descriptive output for sticky vendor options #750)

A previous attempt to change this default was reverted because solver errors gave no indication that vendor locking was the cause. The new hint in print_resolve_hints() addresses that by detecting RULE_UPDATE problems and telling the user how to override the restriction.

Closes: #712 #750 SWMBZBUGSM-153 BZ#2219624

CI Tests: rpm-software-management/ci-dnf-stack#1839

[Conan-Kudo]

I think the descriptive hint essentially requires that we have a new top level CLI arg like I suggested (e.g --[no-]allow-vendor-change).

Additionally, are we not able to force vendor changes for packages individually with --from= or by using full NEVRAs?

[fhbash]

Removing from this PR the default value change... we'll keep the old state as it is.

@Conan-Kudo after discuss with the team, we decide to merge this PR without the default value change and the new CLI argument. We'll do an new PR for these changes for the next cicle (F45).

[evan-goode]

To clarify, we think it's too close to F44 GA, and we'd like to submit a change proposal for F45 and have this spend some time in Rawhide.

[Conan-Kudo]

Sure, makes sense to me. We should be able to get the CLI argument in before flipping the switch for F45 too, no?

[Conan-Kudo]

That is, everything but flipping the default from True to False can be done for F44.