tests: don't enforce dnf4 installation into bootstrap

Mock has a build-in abstraction for in-bootstrap DNF version (or YUM),
there's no need to check if DNF exists on host (this whole dropped test
code comes from the pre-bootstrap era).

mock/integration-tests/runtests.sh

@@ -44,15 +44,7 @@ else
     MOCKSRPM=$1
 fi
 
-if [ -e /usr/bin/dnf ]; then
-    header "pre-populating the cache (DNF)"
-    runcmd "$MOCKCMD --init --dnf"
-    header "clean up"
-    runcmd "$MOCKCMD --offline --clean"
-else
-    header "pre-populating the cache (YUM)"
-    runcmd "$MOCKCMD --init"
-fi
+runcmd "$MOCKCMD --init"
 header "installing dependencies for $MOCKSRPM"
 runcmd "$MOCKCMD --disable-plugin=tmpfs --installdeps $MOCKSRPM"
 if [ ! -e $CHROOT/usr/include/python* ]; then