Log forwarded metadata keys to Splunk in RHOCP 4

Issue

• It's log forwarded the logs to Splunk and the name of the fields received is not the recommended by Splunk for the Event metadata
• When log forwarding to Splunk from the Red Hat Logging stack, the key host is not received in the Event metadata, instead, it's visible the key hostname
• When log forwarding to Splunk from the Red Hat Logging stack, the key source is not received being the expected content in the Event metadata key file