Fixes the three `FullEditor.spec.js` slash-menu failures that appeared
after #15291 and #15296 crossed on develop: #15296 added slash-menu
specs that assert real translated labels ("Divider", "Heading 1"), while
#15291 emptied the global i18n catalogue in the vitest setup, so `t()`
started returning raw keys like `SLASH_COMMANDS.DIVIDER`.
The spec now calls `withFullI18n()` from the `test-i18n` helper
introduced in #15291, opting into the full message catalogue the same
way `MacroProperties.spec.js` does. Test-only change, no production code
touched.
Related: https://github.com/chatwoot/chatwoot/pull/15291
eb375c45ce