test: skip flaky test_virtio_mem_hotplug_hotunplug

The GET /hotplug/memory API call intermittently exceeds the maximum
duration assertion (~800-1200ms observed), making the test flaky.
Skip until the latency is investigated.

Signed-off-by: Jay Chung <jaehoc@amazon.com>

Author: not4s

tests/integration_tests/performance/test_hotplug_memory.py

@@ -252,6 +252,9 @@ def check_hotunplug(uvm, requested_size_mib):
         assert rss_after < rss_before, "RSS didn't decrease"
 
 
+@pytest.mark.skip(
+    reason="GET /hotplug/memory intermittently exceeds the duration threshold"
+)
 def test_virtio_mem_hotplug_hotunplug(uvm_any_memhp):
     """
     Check that memory can be hotplugged into the VM.