No longer install the Jupyter extension by default (#20218)

For #18073

---------

Co-authored-by: Brett Cannon <brett@python.org>

README.md

@@ -37,7 +37,9 @@ Extensions installed through the marketplace are subject to the [Marketplace Ter
 
 ## Jupyter Notebook quick start
 
-The Python extension and the [Jupyter extension](https://marketplace.visualstudio.com/items?itemName=ms-toolsai.jupyter) work together to give you a great Notebook experience in VS Code.
+The Python extension no longer offers support for Jupyter notebooks out of the box. However, it works with the [Jupyter extension](https://marketplace.visualstudio.com/items?itemName=ms-toolsai.jupyter) to provide you a great Python notebook experience in VS Code.
+
+- Install the [Jupyter extension](https://marketplace.visualstudio.com/items?itemName=ms-toolsai.jupyter).
 
 -   Open or create a Jupyter Notebook file (.ipynb) and start coding in our Notebook Editor!
 

gulpfile.js

@@ -82,9 +82,13 @@ async function addExtensionPackDependencies() {
     // extension dependencies need not be installed during development
     const packageJsonContents = await fsExtra.readFile('package.json', 'utf-8');
     const packageJson = JSON.parse(packageJsonContents);
-    packageJson.extensionPack = ['ms-toolsai.jupyter', 'ms-python.vscode-pylance'].concat(
+    packageJson.extensionPack = ['ms-python.vscode-pylance'].concat(
         packageJson.extensionPack ? packageJson.extensionPack : [],
     );
+    // Remove potential duplicates.
+    packageJson.extensionPack = packageJson.extensionPack.filter(
+        (item, index) => packageJson.extensionPack.indexOf(item) === index,
+    );
     await fsExtra.writeFile('package.json', JSON.stringify(packageJson, null, 4), 'utf-8');
 }