Correct line breaks in settings.default.json
The example file of settings.default.json has some line breaks, so it breaks the JSON validation, i.e. https://jsonlint.com/, and as a consequence, the settings.default.json file is not read during CiviCRM install, without any warning or error message.
Correcting the line breaks by adding
\n where required corrects the issue, see /copy_metadata <!4 (merged)t>