Align matrix.to url scheme with matrix: uri scheme

See https://github.com/matrix-org/matrix-doc/pull/2312

E.g. use https://matrix.to/#/u/her:example.org rather than https://matrix.to/#/@her:example.org

This would make it easy to convert a matrix.to link to a matrix: link, just remove the `.to/#/` part.

Start by reviewing the referenced matrix-doc pull request 2312 and locating the matrix.to URL generation or redirect entry point. Verify how user links are formed, then confirm the resulting URL uses the matrix: URI-compatible path and that the conversion described in the issue works.

Written by the indexing model from the issue text.