Palo Alto Input not parsing `VendorFields.VENDOR_PRIVATE_IP`, field is either NOT present when it should be or contains 0.0.0.0

Palo Alto Networks TCP (PAN-OS v9+) input not parsing `VendorFields.VENDOR_PRIVATE_IP`, field is either NOT present when it should be or contains 0.0.0.0

Initially investigating why pan_event_name: gateway-getconfig is not parsing the virtual ip (IP handed out by Global Protect gateway, internal IP used on that network).

Looking at the mappings via https://github.com/Graylog2/graylog2-server/blob/master/graylog2-server/src/main/java/org/graylog/integrations/inputs/paloalto9/PaloAlto9xTemplates.java#L242 and comparing to the comma separated message, the fields line up correctly, the data is in the message, so it is unclear why its not being parsed.

## Expected Behavior

VENDOR_PRIVATE_IP is parsed from the palo alto log message

## Current Behavior

VENDOR_PRIVATE_IP is either missing from message it should exist for, OR VENDOR_PRIVATE_IP only has 0.0.0.0

## Possible Solution

## Steps to Reproduce (for bugs)

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## Context

This is related to a deal we're working on closing and is very important for tracking users/devices against their virtual IP.

## Your Environment

* Graylog Version: Graylog Cloud 5.1.6 (362)