Update gating tests in /plans/tier0.fmf

plans/tier0.fmf

@@ -1,4 +1,73 @@
-summary: Foo
-execute:
-    script: leapp --help
+# These test plans were created manually based on information taken from
+# https://gitlab.cee.redhat.com/oamg/leapp-tests/-/blob/main/config.yaml. The tmt definitions can be simplified, once
+# https://github.com/teemtee/tmt/issues/1770 is implemented.
 
+summary: Internal Tier0 tests
+
+environment:
+    SOURCE_RELEASE: '8.10'
+    TARGET_RELEASE: '9.5'
+
+context:
+    distro: rhel-8.10
+    distro_target: rhel-9.5
+
+adjust:
+    enabled: false
+    when: distro == centos-stream-8
+
+/customrepos_upgrade_happy_path:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/destructive/customrepos/basic_upgrade/upgrade_happy_path
+            ref: main
+
+/oamg3661_two_reboots:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/destructive/customrepos/oamg/oamg3661_two_reboots
+            ref: main
+
+/oamg9094_datainrpm_predownload_then_install:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/destructive/customrepos/oamg/oamg9094_datainrpm_predownload_then_install
+            ref: main
+
+/oamg9299_devtmpfs_in_fstab:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/destructive/customrepos/oamg/oamg9299_devtmpfs_in_fstab
+            ref: main
+
+/rhsm_upgrade_happy_path:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/destructive/rhsm/upgrade_happy_path
+            ref: main
+
+/customrepos_tier0only:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/nondestructive/customrepos/tier0only
+            ref: main
+
+/none_tier0only:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/nondestructive/none/tier0only
+            ref: main
+
+/rhsm_tier0only:
+    plan:
+        import:
+            url: https://gitlab.cee.redhat.com/oamg/leapp-tests
+            name: /plans/nondestructive/rhsm/tier0only
+            ref: main