When generating sectionLoads config, dbctl knows to rewrite 's3' as 'DEFAULT': https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/conftool/+/refs/heads/master/conftool/extensions/dbconfig/config.py#125
However, it does not do the same for readOnlyBySection because we don't tell it to:
https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/conftool/+/refs/heads/master/conftool/extensions/dbconfig/config.py#99