Remove workaround to create the postgres db (fix #886)

This reverts commit 4df6f79568.
The upstream bug has been fixed in https://github.com/nextcloud/server/pull/15187

Signed-off-by: J0WI <J0WI@users.noreply.github.com>

.examples/docker-compose/insecure/postgres/apache/db.env

@@ -1,2 +1,3 @@
 POSTGRES_PASSWORD=
-POSTGRES_USER=postgres
+POSTGRES_DB=nextcloud
+POSTGRES_USER=nextcloud

.examples/docker-compose/insecure/postgres/apache/docker-compose.yml

@@ -18,7 +18,6 @@ services:
       - nextcloud:/var/www/html
     environment:
       - POSTGRES_HOST=db
-      - POSTGRES_DB=nextcloud
     env_file:
       - db.env
     depends_on:

.examples/docker-compose/insecure/postgres/fpm/db.env

@@ -1,2 +1,3 @@
 POSTGRES_PASSWORD=
-POSTGRES_USER=postgres
+POSTGRES_DB=nextcloud
+POSTGRES_USER=nextcloud

.examples/docker-compose/insecure/postgres/fpm/docker-compose.yml

@@ -16,7 +16,6 @@ services:
       - nextcloud:/var/www/html
     environment:
       - POSTGRES_HOST=db
-      - POSTGRES_DB=nextcloud
     env_file:
       - db.env
     depends_on:

.examples/docker-compose/with-nginx-proxy/postgres/apache/db.env

@@ -1,2 +1,3 @@
 POSTGRES_PASSWORD=
-POSTGRES_USER=postgres
+POSTGRES_DB=nextcloud
+POSTGRES_USER=nextcloud

.examples/docker-compose/with-nginx-proxy/postgres/apache/docker-compose.yml

@@ -19,7 +19,6 @@ services:
       - LETSENCRYPT_HOST=
       - LETSENCRYPT_EMAIL=
       - POSTGRES_HOST=db
-      - POSTGRES_DB=nextcloud
     env_file:
       - db.env
     depends_on:

.examples/docker-compose/with-nginx-proxy/postgres/fpm/db.env

@@ -1,2 +1,3 @@
 POSTGRES_PASSWORD=
-POSTGRES_USER=postgres
+POSTGRES_DB=nextcloud
+POSTGRES_USER=nextcloud

.examples/docker-compose/with-nginx-proxy/postgres/fpm/docker-compose.yml

@@ -16,7 +16,6 @@ services:
       - nextcloud:/var/www/html
     environment:
       - POSTGRES_HOST=db
-      - POSTGRES_DB=nextcloud
     env_file:
       - db.env
     depends_on: