Clean up wmo root files

[janbrasna]

One-line summary

Removes wmo-specific content from root_files and configs.

Significant changes and points to review

1. The internal CA certs are no longer used and mostly expired, only linked from wikimo to wmo, not needed here.
2. The banner (only content of /images in root) is a wmo legacy to preserve links, not needed here.
3. The matrix well-knowns are not needed here (they verify EMS instance at chat.m.o with asset URLs etc. and provide some domain-based discovery for the Element/Matrix at mozorg…)
4. Removed nonlocale entries incl. for redirects long gone…
5. (Also updates the domain/URL in info.txt)