Fix: rename test route to testerror/

[angela-tran]

I needed this change while testing #2694.

In 746f322, we introduced an error/ route to core's URLconf. We overlooked that in the root URLconf, there already was an error/ route if DEBUG=True, which is for the purpose of testing Sentry.

That change was in May 2024, so I'm not sure how we've been able to test Sentry updates since then. For example, in November 2024, I was somehow able to hit the root error/ and trigger the RuntimeError("Test error").

Today, what I saw was that when I go to error/, I hit the core error/ and see the Error page. No Sentry notification is sent:

I had to change the route name to something else in order to hit the root path and then a Sentry notification was sent:

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
benefits
urls.py					51
Project Total

This report was generated by python-coverage-comment-action

[thekaveman]

Interesting. I haven't seen this problem before either 🤔

But I was able to confirm the problem, and this change matches our testsecret/ registration.