2.4.0rc4: Feature improvement

What's Changed

• Fix cloud scripts heredoc spacing by @SYangster in #2059
• Step-by-step SAG with ModelLearner and Executor by @SYangster in #2051
• Restore non-aio GRPC and a few improvements by @yanchengnv in #2058
• Add how-to guide for large models by @IsaacYangSLA in #2062
• Enhance PT Client API examples by @YuanTingHsieh in #2057
• Removed 4G Limit on non-bytes data by @nvidianz in #2067
• Add support for listen_host by @IsaacYangSLA in #2073
• Add financial example with xgboost by @ZiyueXu77 in #2054
• Update XGBoost examples by @SYangster in #2066
• Client api use exchange task by @YuanTingHsieh in #2070

Full Changelog: 2.4.0rc3...2.4.0rc4