[Bugfix][Core] Use torch.cuda.memory_stats() to profile peak memory usage (#9352)

Signed-off-by: Joe Runde <Joseph.Runde@ibm.com>

tests/entrypoints/llm/test_lazy_outlines.py

@@ -26,10 +26,12 @@ def test_lazy_outlines(sample_regex):
     # make sure outlines is not imported
     assert 'outlines' not in sys.modules
 
+    # The second LLM needs to request a higher gpu_memory_utilization because
+    # the first LLM has already allocated a full 30% of the gpu memory.
     llm = LLM(model="facebook/opt-125m",
               enforce_eager=True,
               guided_decoding_backend="lm-format-enforcer",
-              gpu_memory_utilization=0.3)
+              gpu_memory_utilization=0.6)
     sampling_params = SamplingParams(temperature=0.8, top_p=0.95)
     outputs = llm.generate(
         prompts=[