go 1.18 for apm pipeline

[v1v]

What does this PR do?

Go Version is normally being driven by Beats and similar projects. So let's use the same versioning

Why is it important?

Avoid weird surprises regarding the version used in the pipeline:

• ci: force GO_VERSION elastic-agent#1204

[apmmachine]

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• Start Time: 2022-09-15T13:44:00.623+0000

• Duration: 4 min 14 sec

Test stats 🧪

Test	Results
Failed	0
Passed	21
Skipped	0
Total	21

💚 Flaky test report

Tests succeeded.

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