fix(test/live): skip partial-return capacity test when weighted scenario yields <2 instances

EC2Fleet Maintain + spot uses weighted vmTypes, so capacity_to_request=4
can be fulfilled by a single physical instance with WeightedCapacity=4.
The partial-return-reduces-capacity test needs at least 2 physical
instances to terminate one and verify the other survives.

Mirrors the existing skip in test_partial_return_terminates_instance_only
(line 2237).

Author: fgogolli

tests/providers/aws/live/test_onaws.py

@@ -1959,7 +1959,10 @@ def test_partial_return_reduces_capacity(setup_host_factory_mock_with_scenario,
     log.info("1.6: Extracting provisioned instance information")
     machines = status_response["requests"][0]["machines"]
     machine_ids = [m.get("machineId") or m.get("machine_id") for m in machines]
-    assert len(machine_ids) >= 2, "Partial return test requires capacity > 1"
+    if len(machine_ids) < 2:
+        pytest.skip(
+            f"Only {len(machine_ids)} physical instance(s) provisioned (weighted capacity scenario) — need 2+ for partial return test"
+        )
     log.info("Provisioned %d instances: %s", len(machine_ids), machine_ids)
 
     # === STEP 2: PARTIAL RETURN AND CAPACITY VERIFICATION ===