Unable to initialize PostgreSQL database in Plesk: start service postgresql failed psql: could not connect to server:

Checking PostgreSQL status shows the following:

# systemctl status postgresql.service
● postgresql.service - PostgreSQL database server
Loaded: loaded (/usr/lib/systemd/system/postgresql.service; disabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Fri 2020-03-27 22:56:17 WIB; 26s ago
Process: 9181 ExecStartPre=/usr/bin/postgresql-check-db-dir ${PGDATA} (code=exited, status=1/FAILURE)

There are the following records in /var/log/messages file:

Mar 27 22:56:17 localhost systemd: Starting PostgreSQL database server...
Mar 27 22:56:17 localhost postgresql-check-db-dir: "/var/lib/pgsql/data" is missing or empty.
Mar 27 22:56:17 localhost postgresql-check-db-dir: Use "postgresql-setup initdb" to initialize the database cluster.

Manual initialization fails with:

# service postgresql initdb
Hint: the preferred way to do this is now "postgresql-setup initdb"
Initializing database ... failed, see /var/lib/pgsql/initdb.log

In /var/lib/pgsql/initdb.log file:

The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.
The database cluster will be initialized with locale "C".
The default database encoding has accordingly been set to "SQL_ASCII".
The default text search configuration will be set to "english".
initdb: directory "/var/lib/pgsql/data" exists but is not empty
If you want to create a new database system, either remove or empty
the directory "/var/lib/pgsql/data" or run initdb
with an argument other than "/var/lib/pgsql/data".