panw: update mapping of zone fields in visualisations

[efd6]

What does this PR do?

These were missed when the source and destination zone ingestion was
removed.

See b6a86b2#diff-59b7510d3715bf1d6cc9619d4ae36134571ae31e2bb54c717b653287ac4cc288L59-L62 for details.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

Author's Checklist

• [ ]

How to test this PR locally

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• Start Time: 2022-05-17T00:20:23.344+0000

• Duration: 18 min 34 sec

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Test	Results
Failed	0
Passed	33
Skipped	0
Total	33

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Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (6/6)	💚 3.589
Classes	100.0% (6/6)	💚 3.589
Methods	100.0% (34/34)	💚 11.714
Lines	87.059% (814/935)	👎 -1.973
Conditionals	100.0% (0/0)	💚