The cronjob tries to get key from `mastodon` secret instead of
`mastodon-postgresql` - so the cronjob fails with this error:
Error: couldn't find key postgresql-password in Secret [NS]/mastodon
Another solution is to save the postgres password in mastodon secret,
but that means that the password is placed in two places.
Postgresql use <fullname>-postgresql name as secret name.
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