[prometheus] Ensure event.kind is correctly set for pipeline errors

[MakoWish]

What does this PR do?

Modify prometheus integration to correctly set event.kind for pipeline errors and ensure error.message is an array.

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

• For sei: ensure packages set error.kind to "pipeline_error" in on_failure processor #6582

Screenshots

[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: 2023-09-28T16:20:08.810+0000

• Duration: 16 min 25 sec

Test stats 🧪

Test	Results
Failed	0
Passed	9
Skipped	0
Total	9

🤖 GitHub comments

Expand to view the GitHub comments

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

• /test : Re-trigger the build.

[gizas]

LGTM checking other relevant PRs

[MakoWish]

This one is failing for invalid types in ./data_stream/collector/fields/fields.yml and /data_stream/query/fields/fields.yml, but those changes were not pushed by me, and I am not exactly sure how to correct those. According to the error, the type: object is not valid.

[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (0/0)	💚
Files	100.0% (0/0)	💚
Classes	100.0% (0/0)	💚
Methods	66.667% (8/12)	❕
Lines	100.0% (0/0)	💚
Conditionals	100.0% (0/0)	💚

[botelastic]

Hi! We just realized that we haven't looked into this PR in a while. We're sorry! We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1. Thank you for your contribution!

[MakoWish]

Had to fix some conflicts. Would someone mind kicking off another /test and merging if/when done? I don't have permissions to.

[constanca-m]

Done @MakoWish

[elasticmachine]

Package prometheus - 1.13.0 containing this change is available at https://epr.elastic.co/search?package=prometheus