Tracking internal uses of concat that don't allow setting all the kwargs

[jsignell]

What is your issue?

While working on #8778 I encountered some places where concat is used internally but the kwargs are not individually settable: stack and groupby.

#10062 hardcodes them to the old defaults: data_vars="all", coords="different", compat="equals", join="outer"

@dcherian mentioned (https://github.com/pydata/xarray/pull/10062/files#r1978040669) that we might want stricter behavior.