Config Translation only supports `translatable: true` at the top level, but has no validation to indicate this

This should fail like so:

Testing /Users/wim.leers/core/core/modules/config_translation/tests/src/Functional
.                                                                   1 / 1 (100%)

Time: 00:13.523, Memory: 10.00 MB

OK (1 test, 28 assertions)

Unsilenced deprecation notices (12)

  12x: The `field.value.created.mapping` config schema specifies the `translatable` property, but the config_translation module only supports this for types.
    12x in ConfigTranslationUiTest::testSourceValueDuplicateSave from Drupal\Tests\config_translation\Functional

The Needs Review Queue Bot → tested this issue. It fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

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Try to fix CCF error.

NR so the bot can look at #4.

#2 tells us that this should fail, but I can't find any of those errors in the output, is that because the fail patch is no longer there?

In any case, back to needs work for the todo in the code (making it recursive).