[ROCm][CI] Increase the memory threshold for test_deep_sleep_fp8_kvcache (#30104)

Signed-off-by: charlifu <charlifu@amd.com>

tests/basic_correctness/test_cumem.py

@@ -260,13 +260,18 @@ def test_deep_sleep_fp8_kvcache():
     llm.sleep(level=2)
 
     used_bytes = current_platform.get_current_memory_usage() - used_bytes_baseline
-    assert used_bytes < 3 * GiB_bytes
+
+    # Rocm uses more memory for CudaGraphs, so we add 2 GiB more for the threshold
+    rocm_extra_mem_bytes = 2 * GiB_bytes if current_platform.is_rocm() else 0
+    mem_threshold_after_sleep = 3 * GiB_bytes + rocm_extra_mem_bytes
+    assert used_bytes < mem_threshold_after_sleep
 
     llm.wake_up(tags=["weights"])
     llm.collective_rpc("reload_weights")
 
     used_bytes = current_platform.get_current_memory_usage() - used_bytes_baseline
-    assert used_bytes < 4 * GiB_bytes
+    mem_threshold_after_wake_up = 4 * GiB_bytes + rocm_extra_mem_bytes
+    assert used_bytes < mem_threshold_after_wake_up
 
     # now allocate kv cache and cuda graph memory
     llm.wake_up(tags=["kv_cache"])