fix: Update disagg configs for trtllm 1.0.0rc4 changes (release/0.4.0)

[rmccorm4]

Overview:

With update to TRTLLM 1.0.0rc4, various config field names and requiements have changed, this PR updates them across all example configs.

Agg configs were updated with most of these in #2217, but some of the fixes were missed in the disagg configs.

Fixes nvbugs/5430986:

1. cache_transceiver_config is now a required field in the YAML config to enable disaggregation.

AssertionError: kv_cache_transceiver is disabled, please set 'cache_transceiver_config: backend:` in config file for disaggregated serving

Fixes nvbugs/5431299:

2. kv_cache_dtype is now kv_cache_config.dtype
3. autotuner_enabled is now enable_autotuner
4. pytorch_weights_path is now speculative_model_dir, which fixes:

ERROR ... Path to EAGLE3 weights must be specified.

NOTE: I will bring these fixes back to main branch quickly afterwards - focus is on release for sanity testing first.

[KrishnanPrash]

LGTM.

[rmccorm4]

FYI - test-end-to-end-trtllm-multi-GPU appears to be flaky. Sometimes passing, sometimes failing, on this branch and on other unrelated branches as well. Should be investigated separately.