improve the Tier1 test plan

To avoid known failures, do not run the tests which have the
failinfedora tag.
To make more tests working, enable the EPEL repository too.

plans/tests.fmf

@@ -1,8 +1,18 @@
 summary: Tier 1 selinux-policy test plan
 discover:
-    how: fmf
-    url: https://src.fedoraproject.org/tests/selinux.git
-    filter: "tier: 1 | component: selinux-policy"
+  how: fmf
+  url: https://src.fedoraproject.org/tests/selinux.git
+  filter: "tier:1 & tag:-failinfedora | component:selinux-policy & tag:-failinfedora"
+prepare:
+  how: shell
+  script: yum config-manager --set-enabled epel ; sed -i 's/CentOS Stream/Red Hat Enterprise Linux/' /etc/redhat-release
 execute:
-    how: tmt
+  how: tmt
+adjust:
+  - when: distro ~= rhel-9
+    prepare+:
+       script+<: yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm
+  - when: distro ~= rhel-8
+    prepare+:
+       script+<: yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm