gcp: fix type of dns.answers.ttl

[efd6]

What does this PR do?

This converts dns.answers.ttl to long during document parsing to conform to ECS spec for this field.

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

Related issues

• Closes GCP-DNS Field Type Mismatch #4361

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• Start Time: 2022-10-04T20:34:01.887+0000

• Duration: 19 min 58 sec

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Passed	82
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Total	82

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Data stream	Previous EPS	New EPS	Diff (%)	Result
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Name	Metrics % (covered/total)	Diff
Packages	100.0% (5/5)	💚
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Classes	100.0% (5/5)	💚 2.573
Methods	90.816% (89/98)	👍 0.636
Lines	95.752% (1375/1436)	👍 4.17
Conditionals	100.0% (0/0)	💚

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