Merge branch 'js/gettext-poison-fixes'

The `maint-2.30` branch accumulated quite a few fixes over the past two
years. Most of those fixes were originally based on newer versions, and
while the patches cherry-picked cleanly, we weren't diligent enough to
pay attention to the CI builds and the GETTEXT_POISON job regressed.
This topic branch fixes that.

* js/gettext-poison-fixes
  t0033: GETTEXT_POISON fix
  t0003: GETTEXT_POISON fix, part 1
  t0003: GETTEXT_POISON fix, conclusion
  t5619: GETTEXT_POISON fix
  t5604: GETTEXT_POISON fix, part 1
  t5604: GETTEXT_POISON fix, conclusion