Remove migration generating lets encrypt key
Don't generate private_key if database is readonly
For reference:
This reverts commit 988a7f70489b99383b95e9f271a2caf6bb5b3a44.
This reverts commit 21acbe531592d55caf0e5b8716a3b551dafd6233.
Storing this key in secrets.yml was a bad idea,
it would require users using HA setups to manually
replicate secrets across nodes during update,
it also needed support from omnibus package
* Revert "Generate Let's Encrypt private key"
This reverts commit 444959bfa0.
* Add Let's Encrypt private key to settings
as encrypted attribute
* Generate Let's Encrypt private key
in database migration
