packaging: stop installing i18n files
The WiX installer has been shipping the content of the i18n/
directory since it was introduced in 2010 in 1e022c88a0a5.
And the installer was subsequently refactored to only ship
the .po files and hggettext.
The .po files and the hggettext script are only used at build
time to produce .mo files, which Mercurial does use at run-time.
It doesn't make sense to install these files on Windows. So
this commit stops doing that.
This change further converges the file layout of the Inno and
Differential Revision: https://phab.mercurial-scm.org/D7165