Remove .go-version and source Go version from go.mod

[carsonip]

Motivation/summary

Use go.mod as the single source of truth for Go versioning by removing .go-version and replacing all remaining references that depended on it.

This removes version drift risk between files and keeps packaging, CI checks, and local Tilt behavior aligned with the build configuration already used by actions/setup-go and Make targets.

Checklist

• Update CHANGELOG.asciidoc
• Documentation has been updated

For functional changes, consider:

• Is it observable through the addition of either logging or metrics?
• Is its use being published in telemetry to enable product improvement?
• Have system tests been added to avoid regression?

How to test these changes

• Verify no .go-version references remain:
  • rg "\\.go-version"
• Verify Go version resolution now comes from go.mod:
  • rg "grep '\^go ' go.mod|go-version-file: go.mod|go-version-file: systemtest/go.mod|go-version-file: integrationservertest/go.mod"
• Optionally run:
  • make package-snapshot

Related issues

None.

Made with Cursor

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[kruskall]

this is gonna run quite often :(

[carsonip]

that's true 😞

[mergify]

This pull request does not have a backport label. Could you fix it @carsonip? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8.19 is the label to automatically backport to the 8.19 branch.
• backport-9./d is the label to automatically backport to the 9./d branch. /d is the digit.
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 7835e01

[v1v]

Tiltfile also uses it