Allow obsoletion of protected packages

As described at the end of this comment:
rpm-software-management/dnf#1926 (comment)

There should be some mechanism for replacing even protected packages,
e.g. to upgrade DNF to DNF 5. Obsoleting a protected package is less
likely to happen accidentally than removing it. But this change does
mean that a protected package could be obsoleted, and then the obsoleter
could be removed, which is perhaps not ideal.

IMO a better, more "declarative" way, might be to disallow any
transaction that would result in a protected package no longer being
provided. But I'm not sure how to do this without modifying libsolv.

libdnf/goal/Goal.cpp

@@ -1631,8 +1631,6 @@ Goal::Impl::protectedInRemovals()
     if ((!protectedPkgs || !protectedPkgs->size()) && !protect_running_kernel)
         return false;
     auto pkgRemoveList = listResults(SOLVER_TRANSACTION_ERASE, 0);
-    auto pkgObsoleteList = listResults(SOLVER_TRANSACTION_OBSOLETED, 0);
-    map_or(pkgRemoveList.getMap(), pkgObsoleteList.getMap());
 
     removalOfProtected.reset(new PackageSet(pkgRemoveList));
     Id id = -1;