Drop redirect usage from URL references

[jchristgit]

trafficstars

As mentioned in the development channels, there are some spots where we are redirecting from the site to the redirects app, whilst we should use the new location instead, possibly related to the deploy preview support.

Find those spots and switch to use reverse instead (or generate proper URLs otherwise).

[jchristgit]

See for example https://github.com/python-discord/site/blob/main/pydis_site/apps/content/resources/guides/pydis-guides/how-to-contribute-a-page.md. Consider writing a script to grep through and find these cases.