Use dependency injection on redirect\Form\RedirectForm

Assigning to myself as I'm triaging all RTBC issues.

Thanks for the issue, patch, and review. I see there is also this issue:

📌 Use dependency injection for redirect classes Needs review

so it would be preferable to update all the dependency injection in one patch given this patch isn't that big.

Note, we've been discussing contribution gaming at length in a Drupal Slack channel... IMO splitting up issues like this one and the one above can be considered issue credit gaming. Here there is mention of "bulk posting" which is similar:

https://www.drupal.org/drupalorg/docs/marketplace/abuse-of-the-contribut... →

I think it would be best to update the 📌 Use dependency injection for redirect classes Needs review to include this code.

I'm marking postponed for now until this can happen.

Adding related issue.