Add back hardcoded self-protection of dnf

Now that obsoletion of protected packages is allowed
(#1610), it's best
to hardcode the protection of dnf here instead of using the file in
/etc/dnf/protected.d. This way, DNF 4 cannot uninstall itself, but DNF 5
can uninstall DNF 4, and likewise (given a similar change in DNF 5), DNF
5 cannot uninstall itself, but DNF 4 can uninstall DNF 5.

Related: https://bugzilla.redhat.com/show_bug.cgi?id=2221905
Related: https://bugzilla.redhat.com/show_bug.cgi?id=2221907

= changelog =
msg: Allow dnf to be removed by DNF 5
type: enhancement

libdnf/conf/ConfigMain.cpp

@@ -313,8 +313,9 @@ class ConfigMain::Impl {
         }
     };
 
-    OptionStringList protected_packages{resolveGlobs("glob:/etc/yum/protected.d/*.conf " \
-                                          "glob:/etc/dnf/protected.d/*.conf")};
+    OptionStringList protected_packages{resolveGlobs("dnf " \
+                                                     "glob:/etc/yum/protected.d/*.conf " \
+                                                     "glob:/etc/dnf/protected.d/*.conf")};
     OptionString username{""};
     OptionString password{""};
     OptionBool gpgcheck{false};