[DevTask] Add custom node testing checkbox to issue template (#4041)

Author: christian-byrne

.github/ISSUE_TEMPLATE/bug-report.yaml

@@ -15,6 +15,15 @@ body:
         - **3:** You confirmed that the bug is not caused by a custom node. You can disable all custom nodes by passing
         `--disable-all-custom-nodes` command line argument.
 
+  - type: checkboxes
+    id: custom-nodes-test
+    attributes:
+      label: Custom Node Testing
+      description: Please confirm you have tried to reproduce the issue with all custom nodes disabled.
+      options:
+        - label: I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)
+          required: true
+
   - type: textarea
     attributes:
       label: Frontend Version