Re-enable dynamic tuning of shared_buffers
Re-enable dynamic tuning of shared_buffers

In commit c74a62f4fcc448069f5e9a579322ea6deec1bdc5 the configuration was changed to a Patroni 1.0 compatible
configuration. However, shared_buffers was pinned to 500MB with this.

zalando/spilo,zalando/spilo,zalando/spilo