It is now also possible to point the configuration path to a directory instead of a file.
Patroni will find all yml files in the directory and apply them in sorted order
Close https://github.com/zalando/patroni/issues/1669
So far Patroni was enforcing the same value of `wal_keep_segments` on all nodes in the cluster. If the parameter was missing from the global configuration it was using the default value `8`.
In pg13 beta3 the `wal_keep_segments` was renamed to the `wal_keep_size` and it broke Patroni.
If `wal_keep_segments` happened to be present in the configuration for pg13, Paroni will recalculate the value to `wal_keep_size` assuming that the `wal_segment_size` is 16MB. Sure, it is possible to get the real value of `wal_segment_size` from pg_control, but since we are dealing with the case of misconfiguration it is not worse time spend on it.
The latest timeline is calculated from the `/history` key in DCS. In case there is no such key or it contains some garbage we consider the node healthy.
Closes https://github.com/zalando/patroni/issues/890
