[CI] Rewrite killall_sglang as Python with CI/local dual mode (#21331)

Co-authored-by: Alison Shao <alison.shao@mac.lan>
Co-authored-by: Alison Shao <alison.shao@MacBook-Pro-D2W773R9CD.local>
Co-authored-by: hnyls2002 <lsyincs@gmail.com>
Co-authored-by: Liangsheng Yin <hnyls2002@gmail.com>

python/pyproject.toml

@@ -163,6 +163,7 @@ vsa = ["torch", "setuptools"]
 
 [project.scripts]
 sglang = "sglang.cli.main:main"
+killall_sglang = "sglang.cli.killall:main"
 
 [tool.setuptools.package-data]
 "sglang" = [