[Fix] "Unable to determine database syntax" on DBInit

[eduardomozart]

Suppress "Unable to determine database syntax" when initializing the database, which could lead sysadmins to think that something is wrong when installing NetXMS (Docker) for the first time. On Error <> 5 it shows the nxdbmgr output as before.

Before:

root@419739ee72ee:/# ./dbinit.sh 
Unable to determine database syntax
NetXMS Database Manager Version 6.1.1 Build 6.1-452-gc20a8a4247

Initializing database...

IMPORTANT: Generated admin password
   Login:    admin
   Password: YnoablTzN24bDXYZ

Please save this password - it will not be shown again.
You will be required to change it on first login.

Database initialized successfully

After:

root@419739ee72ee:/# ./dbinit.sh 
NetXMS Database Manager Version 6.1.1 Build 6.1-452-gc20a8a4247

Initializing database...

IMPORTANT: Generated admin password
   Login:    admin
   Password: 7JZEy6m0oBG2h91i

Please save this password - it will not be shown again.
You will be required to change it on first login.

Database initialized successfully