Skip bgp speaker test on backend topo (#6922)

Signed-off-by: Neetha John <nejo@microsoft.com>

bgpmon and slb peers were removed for storage backend topology as part of sonic-net/sonic-buildimage#12251 which was causing bgp speaker test to fail on t0-backend topology. Hence skipping this test on backend topo

tests/common/plugins/conditional_mark/tests_mark_conditions.yaml

@@ -92,6 +92,12 @@ bgp/test_bgp_gr_helper.py:
     conditions:
       - "'t2' in topo_name"
 
+bgp/test_bgp_speaker.py:
+  skip:
+    reason: "Not supported on topology backend."
+    conditions:
+      - "'backend' in topo_name"
+
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