mgmt|202311: Skip some route tests for standalone topos. (#14483)

What is the motivation for this PR?
Some route tests are not applicable to t0 topos and should be skipped rather than failing unecessarily, negatively impacting pass rate.

How did you do it?
Applied skip conditions to the applicable tests in the tests mark conditions yaml file in sonic-mgmt.

How did you verify/test it?
Ran the route test suite and confirmed that the desired tests are now skipped.

Any platform specific information?
Verified on Arista-7060X6-64PE-256x200G.

tests/common/plugins/conditional_mark/tests_mark_conditions.yaml

@@ -1375,11 +1375,31 @@ restapi/test_restapi_vxlan_ecmp.py:
 #######################################
 #####           route             #####
 #######################################
+route/test_default_route.py:
+  skip:
+    reason: "Does not apply to standalone topos."
+    conditions:
+      - "'standalone' in topo_name"
+
+route/test_route_flap.py:
+  skip:
+    reason: "Does not apply to standalone topos."
+    conditions:
+      - "'standalone' in topo_name"
+
+route/test_route_perf.py:
+  skip:
+    reason: "Does not apply to standalone topos."
+    conditions:
+      - "'standalone' in topo_name"
+
 route/test_static_route.py:
   skip:
-    reason: "Test not supported for 201911 images or older."
+    reason: "Test not supported for 201911 images or older. Does not apply to standalone topos."
+    conditions_logical_operator: OR
     conditions:
       - "release in ['201811', '201911']"
+      - "'standalone' in topo_name"
 
 route/test_static_route.py::test_static_route_ecmp_ipv6:
   # This test case may fail due to a known issue https://github.com/sonic-net/sonic-buildimage/issues/4930.