[O11y][GoLang] Add metric_type for expvar data stream

[harnish-elastic]

• Enhancement

What does this PR do?

• Add missing metric_type for expvar data stream.

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

• Closes [O11y][Golang] Missing metric_type in fields.yml file #7248
• Relates Make Golang GA #7239

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2023-08-31T05:01:05.393+0000

• Duration: 15 min 51 sec

Test stats 🧪

Test	Results
Failed	0
Passed	12
Skipped	0
Total	12

🤖 GitHub comments

Expand to view the GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (2/2)	💚
Files	100.0% (2/2)	💚 3.362
Classes	100.0% (2/2)	💚 3.362
Methods	100.0% (16/16)	💚 8.17
Lines	95.833% (184/192)	👍 7.524
Conditionals	100.0% (0/0)	💚

[devamanv]

Changes look good, just one comment: have we considered treating changes like these to be patch version increments, instead of minor version change i.e. 0.4.1 instead of 0.5.0?

[harnish-elastic]

Changes look good, just one comment: have we considered treating changes like these to be patch version increments, instead of minor version change i.e. 0.4.1 instead of 0.5.0?

Updated, thanks!

[devamanv]

LGTM

[elasticmachine]

Package golang - 0.4.2 containing this change is available at https://epr.elastic.co/search?package=golang