Problem description: If there are no plugin specific parameters defined in zabbix_agent2.conf file, plugin related items don't use default values for their parameters. Once any plugin specific parameter is added in zabbix_agent2.conf file, even if it's not related to the plugin that the items belong to, items start fetching values according to their defaults.

Steps to reproduce:

1. Have a clean Zabbix installation
2. Start agent2 without any modifications to its config file
3. Create a host with any plugin related item (for example redis.ping)
4. Wait for the item to start collecting values
   Result 1: Item is in unsupported status and an error is returned in info column
5. Open zabbix_agent2.conf file and specify any plugin specific parameter, for example uncomment Plugins.SystemRun.LogRemoteCommands=0
6. Restart zabbix_agent2
7. Execute "Check now" option for the previously created plugin related item.
   Result 2: Item status is enabled, item is successfully collecting data.

Expected: Plugin related items should collect data as per their default values of their parameters, even is there are no plugin specific parameters specified in agent2 config file.

Example: