package/network_traffic/tls: fix mapping for tls.detailed.server_certificate_chain

[efd6]

What does this PR do?

This brings the mapping for server_certificate_chain into agreement with the packetbeat code and mapping, fixing #2499.

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

• The mapping for tls.server.certificate_chain in ECS disagrees with this change. I believe this is wrong based on the information required to describe a cert and that the packetbeat code marshals to a []common.MapStr. tls.server.certificate_chain is presumably intended to be filled with a string representation of the chain elements.

How to test this PR locally

elastic-package test system --data-streams tls in the network_traffic package.

Related issues

• Closes Network Packet Capture | TLS Parsing Error #2499

Screenshots

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Build stats

• Start Time: 2022-01-24T16:13:28.064+0000

• Duration: 67 min 50 sec

• Commit: cc73b5e

Test stats 🧪

Test	Results
Failed	0
Passed	103
Skipped	0
Total	103

🤖 GitHub comments

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[andrewkroh]

LGTM and matches Packetbeat's mapping.