The translation module's defaults loader throws a warning on every server
restart after the first run because the upsert method uses `id` as the
unique key, but defaultLocales only contains `code` and `name`.
This causes the upsert to always attempt creation, which fails on the
unique `code` constraint with: "Locale with code: en-US, already exists."
Fix: Fetch existing locales first and map their IDs into defaultLocales
so upsert can properly identify existing records and update them.
0277062fec