build(language-service): install @angular/language-service in root node_modules (#40058)

https://github.com/angular/vscode-ng-language-service/pull/994 changed the
structure of the vscode-ng-language-service repository to be a monorepo,
so @angular/language-service should be installed in root node_modules.

PR Close #40058

packages/language-service/build.sh

@@ -14,6 +14,6 @@ if [[ -z "${extension_repo}" ]]; then
 fi
 
 yarn bazel build --config=release //packages/language-service:npm_package
-pushd "${extension_repo}/server"
+pushd "${extension_repo}"
 yarn add @angular/language-service@file:"${bazel_bin}/packages/language-service/npm_package"
 popd