[HAProxy] set event.module and event.dataset

[mtojek]

What does this PR do?

This PR adds event.module and event.dataset to the integration.

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.
• If I'm introducing a new feature, I have modified the Kibana version constraint in my package's manifest.yml file to point to the latest Elastic stack release (e.g. ^7.13.0).

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

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Build stats

• Build Cause: Pull request #1233 updated

• Start Time: 2021-06-29T10:04:24.044+0000

• Duration: 11 min 39 sec

• Commit: c2a0d20

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Test	Results
Failed	0
Passed	37
Skipped	0
Total	37

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[jsoriano]

Why is this change needed? Wouldn't be better if users of 7.13 can already benefit from this change?

[mtojek]

I think we agreed before not to release changes for older stacks if it isn't necessary. This way changes are added only the latest one.

@andresrc I hope that's ok?

[jsoriano]

Ok, let's continue like this if this is the current convention, but I think this artificially couples packages to versions of the stack, ideally packages should depend on the minor version of the stack that they require to work. Changes that don't affect compatibility with shouldn't need to update this.
This way newer packages could be used by users of older, but otherwise compatible, Kibana versions.