Remove redirect from wiki node talk local task and link directly to the Discourse episode category

[Ambient-Impact]

The current implementation has the following drawbacks:

1. It's slower than it needs to be because it has to figure out and perform a redirect when you follow the link, instead of when outputting the local task.
2. It doesn't open in a new tab/window because it doesn't get marked as an external link, since it's technically internal at the time of rendering it.

Reworking the local task to point directly to the relevant Discourse episode category should fix both of the above drawbacks. We should be able to create a deriver plug-in to do this: https://www.drupal.org/docs/drupal-apis/menu-api/providing-module-defined-local-tasks#dynamic-local-task-generation