Replace sync.Once with sync.OnceFunc/OnceValue/OnceValues

[pietern]

Summary

• Migrate all sync.Once usage to sync.OnceFunc, sync.OnceValue, or sync.OnceValues
• Add a forbidigo lint rule to prevent sync.Once from being reintroduced
• Deduplicate config loading in bundle/direct/dresources

This pull request was AI-assisted by Isaac.

[github-actions]

Approval status: pending

/bundle/ - needs approval

Files: bundle/bundle.go, bundle/direct/dresources/config.go
Suggested: @denik
Also eligible: @anton-107, @shreyas-goenka, @andrewnester, @janniklasrose, @lennartkats-db

/internal/ - needs approval

Files: internal/build/info.go, internal/build/variables.go
Suggested: @simonfaltum
Also eligible: @renaudhartert-db, @hectorcast-db, @parthban-db, @tanmay-db, @Divyansh-db, @tejaskochar-db, @mihaimitrea-db, @chrisst, @rauchy

/libs/apps/ - needs approval

Files: libs/apps/logstream/streamer.go, libs/apps/vite/bridge.go
Teams: @databricks/eng-apps-devex

/libs/cmdio/ - needs approval

Files: libs/cmdio/spinner.go
Suggested: @simonfaltum
Also eligible: @renaudhartert-db, @hectorcast-db, @parthban-db, @tanmay-db, @Divyansh-db, @tejaskochar-db, @mihaimitrea-db, @chrisst, @rauchy

General files (require maintainer)

Files: .golangci.yaml
Based on git history:

• @denik -- recent work in bundle/, bundle/direct/dresources/, ./

_{Any maintainer (@andrewnester, @anton-107, @denik, @shreyas-goenka, @simonfaltum, @renaudhartert-db) can approve all areas.
See OWNERS for ownership rules.}

[simonfaltum]

What is the "why" behind this change? The lint rule is obvious to avoid it in the future but why do we want to avoid it?

[pietern]

All sync.Once usage (in this repo) is to initialize some value or run some function. These are a shortcut.

Found these (and others) when going over the release notes of the past couple of Go releases.