Update gating config for required tests

We no longer use the old beaker+tcms based job in our BaseOS CI
(baseos-ci.redhat-module.tier1-functional). Remove it as required
test and use the Testing Farm+tmt based ones.

Related: RHEL-30073

gating.yaml

@@ -4,4 +4,5 @@ product_versions:
 decision_context: osci_compose_gate_modules
 subject_type: redhat-module
 rules:
-  - !PassingTestCaseRule {test_case_name: baseos-ci.redhat-module.tier1.functional}
+  - !PassingTestCaseRule {test_case_name: baseos-ci.redhat-module.tier0-tmt-x86_64-aarch64.functional}
+  - !PassingTestCaseRule {test_case_name: baseos-ci.redhat-module.tier0-tmt-s390x-ppc64le.functional}