[Refactor] Clean up parallel runtime comments (#40632)

test/registered/unit/mem_cache/test_mamba_donated_alloc_ratio.py

@@ -297,7 +297,6 @@ class TestPPMambaPoolSizing(unittest.TestCase):
             server_args=SimpleNamespace(),
             spec_algorithm=SimpleNamespace(is_none=lambda: True),
             layer_info=SimpleNamespace(start_layer=start, end_layer=end),
-            # The runner carries its placement as plain attributes.
             attn_dp_size=1,
             pp_size=pp_size,
             hybrid_gdn_config=None,

test/registered/unit/mem_cache/test_mem_pool_host.py

@@ -302,10 +302,6 @@ class TestHostMemoryBudget(CustomTestCase):
         )
 
     def test_ranks_per_host_divides_world_size_by_nodes(self):
-        # The launcher slices ranks uniformly across nodes, so the co-located
-        # rank count is world_size // nnodes — no hostname collective.
-        # tp_size=16 states the launch width the count divides -- the
-        # published configuration is where ranks_per_host reads it from.
         with (
             get_context().override_server_args(nnodes=2, tp_size=16),
             unittest.mock.patch.object(