Simplify Router arguments passing and build it in docker image (#9964)

scripts/ci/ci_install_dependency.sh

@@ -45,6 +45,10 @@ fi
 # Install the main package
 $PIP_CMD install -e "python[dev]" --extra-index-url https://download.pytorch.org/whl/${CU_VERSION} $PIP_INSTALL_SUFFIX
 
+# Install router for pd-disagg test
+SGLANG_ROUTER_BUILD_NO_RUST=1 $PIP_CMD install -e "sgl-router" $PIP_INSTALL_SUFFIX
+
+
 if [ "$IS_BLACKWELL" = "1" ]; then
     # TODO auto determine sgl-kernel version
     SGL_KERNEL_VERSION=0.3.8