Revert "Fix updates notification on Fedora 29"

The https://bugzilla.redhat.com/1650446 is fixed for enough time already
(included in all supported distributions). The workaround for the bug
have two issues:
 - may download repository metadata again
 - ignores various settings, including proxy, which breaks it in
   TemplateVM

This reverts commit 8d7313b9287bc7a9c83e8face74a7c09b08e5426.

package-managers/dnf-qubes-hooks.py

@@ -59,28 +59,16 @@ class QubesHooks(dnf.Plugin):
             config = self.read_config(self.base.conf)
 
         if config.getboolean('main', 'notify-updates'):
-            if LooseVersion(dnf.const.VERSION) > '4.0.0':
-                # self.base.transaction empty at this point in dnf4
-                # https://bugzilla.redhat.com/1650446
-                # until fixed, load the repositories again and again check for
-                # updates
-                base = dnf.Base()
-                base.read_all_repos()
-                base.fill_sack()
-                query = base.sack.query()
-                query = query.upgrades()
-                updates = set(query.run())
-            else:
-                # Get all updates available _before_ this transaction
-                query = self.base.sack.query()
-                query = query.upgrades()
-                updates = set(query.run())
-                # Get packages installed in this transaction...
-                just_installed = self.base.transaction
-                # ...and filter them out of available updates
-                for item in just_installed:
-                    for pkg in item.installs():
-                        updates.discard(pkg)
+            # Get all updates available _before_ this transaction
+            query = self.base.sack.query()
+            query = query.upgrades()
+            updates = set(query.run())
+            # Get packages installed in this transaction...
+            just_installed = self.base.transaction
+            # ...and filter them out of available updates
+            for item in just_installed:
+                for pkg in item.installs():
+                    updates.discard(pkg)
             subprocess.call([
                 '/usr/lib/qubes/qrexec-client-vm',
                 'dom0',