po_document/pl.iso-8859-2.po file is misplaced

[Gavin Smith]

I am not happy with the presence of the po_document/pl.iso-8859-2.po file
in the Texinfo sources.  This was added in commit fe9bd340 (2023-08-06).
The reason is that it is unlike all the other translation files in
that directory, in that the file has not been provided by translators.
It has only been placed in that directory to allow a test to run
(t/formats_encodings.t 8bit_document_translations).

This file will not automatically be kept up-to-date with the real Polish
translation.  In the (unlikely?) event of anybody generating Polish output
in the ISO-8859-2 encoding, they may get out-of-date translations, which
would not be the fault of the Polish translation team.

It's not clear to anybody looking at the contents of
po_document where this file comes from and they might assume that they could
update the translation files by deleting all *.po files first.

I see several possible solutions:

* Remove the file and the associated test.  That's my favoured option.

* Get the test to access the translation file elsewhere, somehow, but do
  not otherwise use or install this file.  (I don't know how this would be
  done.)

* Add Makefile rules to generate the file.  The commit message says the
  file was produced "using iconv and manual edition" so it is not clear
  if it is easy to generate the file automatically from pl.po.  If I do
  "diff pl.po pl.iso-8859-2.po" then most of the changes are either
  recoding of translations or updates to the header fields but there are
  a small number of other changes too.

Any comments/preferences?