removal of debian/.gitattributes?

[Lucas Nussbaum <lucas@debian.org>]

Hi,

In many of our packages, we have a debian/.gitattributes file, which is
used to avoid exporting gbp.conf, .gitattributes itself, and
salsa-ci.yml (and sometimes other files, such as lintian-brush.conf).

I could not find any official recommendation about using .gitattributes to
avoid exporting those files, nor a rationale.

One side effect is that one cannot just use `gbp import-dsc` to import
into git an upload that is missing (for example an NMU, or a team upload
that wasn't pushed) since in that case, the export-ignored files would
get removed in the git history.

So I wonder if we should just remove them all. What do you think?

Lucas