fix(db): update MySQL collation from utf8mb4_general_ci to utf8mb4_bin

The server uses utf8mb4_bin in both Setup/MySQL.php (database creation)
and Repair/Collation.php (migration). The docs were recommending
utf8mb4_general_ci which contradicts actual server behavior.

Update both the my.cnf snippet and CREATE DATABASE example.

Fixes #1565

Signed-off-by: John Molakvoæ (skjnldsv) <skjnldsv@protonmail.com>

Author: skjnldsv

admin_manual/configuration_database/linux_database_configuration.rst

@@ -89,7 +89,7 @@ Your :file:`/etc/mysql/my.cnf` could look like this:
 
   [mysqld]
   character_set_server = utf8mb4
-  collation_server = utf8mb4_general_ci
+  collation_server = utf8mb4_bin
   transaction_isolation = READ-COMMITTED
   binlog_format = ROW
   innodb_large_prefix=on
@@ -142,7 +142,7 @@ Then a **mysql>** or **MariaDB [root]>** prompt will appear. Now enter the follo
 ::
 
   CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
-  CREATE DATABASE IF NOT EXISTS nextcloud CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
+  CREATE DATABASE IF NOT EXISTS nextcloud CHARACTER SET utf8mb4 COLLATE utf8mb4_bin;
   GRANT ALL PRIVILEGES on nextcloud.* to 'username'@'localhost';
 
 You can quit the prompt by entering::