[BUG] Invoking a Deactivated Source HTTP Webhook Returns 200 Response - Used to return 400

**Describe the bug**
The the behavior of Deactivating a Source HTTP Webhook changed. It was returning a 400 bad request for years when deactivated, but now returns a 200 with a custom response leading to the documentation.

**To Reproduce**
Steps to reproduce the behavior:
1. Create a simple Webhook Source
2. Go to the created pipedream uri for the webhook --> a 200 OK response is returned
3. Deactivate the Webhook manually or through the REST API
https://pipedream.com/docs/api/rest/#update-a-source
4. Go to the created pipedream uri for the webook --> a 200 OK response is returned

**Expected behavior**
A 400 Bad Request response is returned.

**Screenshots**
The returned response:

**Desktop (please complete the following information):**
- OS: Windows
- Browser: Happens on all browsers/HTTP clients
- Version: N/A

**Smartphone (please complete the following information):**
N/A

**Additional context**
A deactivated Webhook used to return a 400 Bad Request for at least 2.5 years, this change only happened recently.