Remove tier 0 functional test from gating.yaml.

These tests are removed from dist-git and are executed
as tier1 or higher tests already.
Signed-off-by: Sahana Prasad <sahana@redhat.com>

gating.yaml

@@ -3,7 +3,6 @@ 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.functional}
   - !PassingTestCaseRule {test_case_name: baseos-ci.brew-build.userspace-fips-mode.functional}
   - !PassingTestCaseRule {test_case_name: baseos-ci.brew-build.tedude.validation}