Remove histogram.counts/values subfields

[mrodm]

What does this PR do?

Remove histogram subfields definitions (counts and values)

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

• Requires System tests fail because fields (counts,values) under histogram type are not defined  elastic-package#905
• Relates package-registry observability integration package-registry#797

[elasticmachine]

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• Start Time: 2022-08-25T09:47:23.758+0000

• Duration: 16 min 3 sec

Test stats 🧪

Test	Results
Failed	0
Passed	5
Skipped	0
Total	5

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (1/1)	💚 2.89
Classes	100.0% (1/1)	💚 2.89
Methods	100.0% (8/8)	💚 10.369
Lines	100.0% (77/77)	💚 8.245
Conditionals	100.0% (0/0)	💚