The salvaged PR added the new key to locales/en.yaml only, so the i18n
catalog-parity test (tests/agent/test_i18n.py::test_catalog_keys_match_english)
failed for all 15 non-English locales. Add the key to every locale with the
English string (matching the existing convention for the untranslated
matrix_cross_room_success key), preserving the {name} placeholder so the
placeholder-parity test also passes.
d00762623b