Don't gate on tier0 test

On RHEL-8, we gate this package on osci.brew-build.tier0.functional, but
in reality, that just runs the test.sh script from the package, and we
already have such a test case (selftest) in
baseos-ci.brew-build.tier1-gating.functional, so drop the former.

This fixes the gating failure caused by the missing tests/ directory
which would normally be required for that tier0 test (and is present in
the RHEL-8 dist-git repo).

gating.yaml

@@ -3,5 +3,4 @@ product_versions:
   - rhel-9
 decision_context: osci_compose_gate
 rules:
-  - !PassingTestCaseRule {test_case_name: osci.brew-build.tier0.functional}
   - !PassingTestCaseRule {test_case_name: baseos-ci.brew-build.tier1-gating.functional}