python: translation fixes
Followup to 292cb01f. That port fixed nearly all i18n issues for the Python plug-ins, and luckily the rest was easy enough to figure out quite quickly :-)
- Remove a stray
_
from a tooltip. - Mark the tooltip for slice syntax in palette-sort translatable, and use the translation.
- Fix translations for new dictionary-style dropdowns in spyro-plus that were not being used.