flymake does not include a prefix indicating the error source when used standalone but does with Eglot

[Niall Dooley]

I have `python-flymake-command' configured as follows via the customize
interface (default value is ("pyflakes")).  Not sure if it is taken into
account when flymake is enabled automatically by Eglot using the
python-lsp-server [1] and its associated python-lsp-ruff [2] plugin.

("ruff" "check" "--quiet" "--stdin-filename=stdin" "-")

When I visit a python file (with known errors) and M-x `flymake-mode' I
see errors reported via flymake but there is prefix in the reports
indicating the errors are coming from ruff.

If I disable `flymake-mode' and M-x `eglot' flymake is started
automatically.  Again I see the same errors reported but this time the
reports include a prefix indicating the errors are coming from ruff.
Very nice if multiple error sources exist.  Note, for now I have no
other other server plugins installed so reports only come from ruff.

Is it possible to have the prefix included in the error reports provided
via flymake when not using eglot?

[1]: https://github.com/python-lsp/python-lsp-server
[2]: https://github.com/python-lsp/python-lsp-ruff