2.4.1rc8: A few bug fixes

What's Changed

• [2.4] Add missing client api test jobs by @YuanTingHsieh in #2531
• [2.4] Update monai readme [skip ci] by @YuanTingHsieh in #2551
• [2.4] Add info for custom data/class [skip ci] by @YuanTingHsieh in #2553
• [2.4] Update ClientAlgo by @YuanTingHsieh in #2566
• [2.4] Fix get_target_names by @SYangster in #2564
• [2.4] Backport AWS VPC/Subnet enhancement from main branch by @IsaacYangSLA in #2568
• [2.4] Upgrade gunicorn by @YuanTingHsieh in #2525
• [2.4] Fix global steps in MLflow example by @chesterxgchen in #2571

Full Changelog: 2.4.1rc7...2.4.1rc8