[Kafka] Add metric_type mapping for partition datastream

[agithomas]

Type of change

• Enhancement

What does this PR do?

Added metric_type mapping for partition datastream

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.

Related issues

• Relates [Kafka] TSDB Enablement #5905

[elasticmachine]

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• Start Time: 2023-04-21T01:52:48.185+0000

• Duration: 14 min 57 sec

Test stats 🧪

Test	Results
Failed	0
Passed	31
Skipped	0
Total	31

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (1/1)	💚 3.026
Classes	100.0% (1/1)	💚 3.026
Methods	72.222% (13/18)	👎 -19.482
Lines	77.778% (56/72)	👎 -14.249
Conditionals	100.0% (0/0)	💚

[ritalwar]

LGTM

[elasticmachine]

Package kafka - 1.5.2 containing this change is available at https://epr.elastic.co/search?package=kafka