rpm-rebuild: remove use of yum, move to dnf

tests/Sanity/rpm-rebuild/runtest.sh

@@ -26,7 +26,7 @@ rlJournalStart
 
     rlPhaseStart FAIL "${PKG_TO_BUILD}"FetchSrcAndInstallBuildDeps
         if ! rlCheckRpm "$PKG_TO_BUILD"; then
-            rlRun "yum install -y $PKG_TO_BUILD ${YUM_SWITCHES}"
+            rlRun "dnf install -y $PKG_TO_BUILD"
             rlAssertRpm "$PKG_TO_BUILD"
         fi
         rlFetchSrcForInstalled "$PKG_TO_BUILD"
@@ -46,7 +46,7 @@ rlJournalStart
         # builddep needs to be run from the srpm, not the spec file, to be able
         # to generate them:
         # https://fedoraproject.org/wiki/Changes/DynamicBuildRequires#rpmbuild
-        rlRun "yum-builddep -y ${SRPM} ${YUM_SWITCHES}"
+        rlRun "dnf builddep -y ${SRPM}"
     rlPhaseEnd
 
     rlPhaseStartTest