[XFAIL: test_crm_available.py] set xfail of test_crm_available on dualtor platform (sonic-net#18874)

What is the motivation for this PR?
To xfail test_crm_available, which has a known issue on broadcom dualtor platform.

How did you do it?
Add xfail in tests_mark_conditions.yaml

How did you verify/test it?
Run test on dualtor platform
=================================================================================================================== short test summary info ====================================================================================================================
XFAIL crm/test_crm_available.py::test_crm_next_hop_group[bjw-can-7260-16-None] - There is a known issue with broadcom dualtor

Any platform specific information?
Broadcom dualtor platform

Author: StormLiangMS

tests/common/plugins/conditional_mark/tests_mark_conditions.yaml

@@ -352,6 +352,12 @@ crm/test_crm.py::test_crm_fdb_entry:
     conditions:
       - "'t0' not in topo_name and topo_type not in ['m0', 'mx']"
 
+crm/test_crm_available.py:
+  xfail:
+    reason: "There is a known issue with broadcom dualtor"
+    conditions:
+      - "https://github.com/sonic-net/sonic-mgmt/issues/18873 and 'dualtor' in topo_name and asic_type in ['broadcom']"
+
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