Modernize the code, make the mysqliConnection easier to use and change mysql command to mariadb

config/services.yaml

@@ -22,9 +22,3 @@ services:
 
     # add more service definitions when explicit configuration is needed
     # please note that last definitions always *replace* previous ones
-
-    App\Service\DatabaseCredentials:
-        arguments:
-            $hostname: '%env(string:DATABASE_HOSTNAME)%'
-            $user: '%env(string:DATABASE_USER)%'
-            $password: '%env(DATABASE_PASSWORD)%'