Determines whether the db:prepare task should seed the database
from db/seeds.rb.
If the `seeds` key is present in the config, `seeds?` will return its
value. Otherwise, it will return `true` for the primary database
and `false` for all other configs.
# File activerecord/lib/active_record/database_configurations/hash_config.rb, line 137
def seeds?
configuration_hash.fetch(:seeds, primary?)
end