Make Beats tech leads the owners of go.mod.

[cmacknz]

We have found the Elastic Agent team is being required to review PRs exclusively because we are the maintainers of go.mod and related files. To avoid making us the bottleneck for these changes, we've created the Beats Tech Leads team so that we can share ownership of these files and unblock our own teams faster.

The alternative is to mark these files as unowned, but since go.mod updates can be critical to product security I don't want to leave these files ownerless. I will also make this group the owner of the CODEOWNER file itself.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @cmacknz? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

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• Start Time: 2023-06-05T15:24:55.274+0000

• Duration: 14 min 22 sec

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Total	3

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