fix: use mapping env syntax in Buildkite pipelines

[wolfeidau]

No description provided.

[buildsworth-bk-app]

Straightforward fix — moving env to Buildkite's mapping form is what makes GOOS: "{{matrix}}" actually take effect during the split matrix build, and .goreleaser.yaml's ko disable condition (isEnvSet "GOOS") leans on that variable being set. The interpolation and quoting look right, and CI #727 is green.

The risk:L1 label landed after I picked this up — I agree it's L1-shaped (a CI-config bug fix with green CI); the only thing giving me slight pause is that it also touches the release pipeline. I'm holding at comment rather than approving solely because of the open question below — the PR also drops the Go cache config and the GOCACHE/GOMODCACHE vars, which is wider than the title. The path forward there is an answer, not a change: if dropping caching is intentional, this is an easy approve.

Want to dig deeper? The full session log is attached to this Buildkite build. Download the session file and open a new pi session with it:

Download the buildsworth logs from build 453, then answer my questions about the findings.

[buildsworth-bk-app]

Question: This also removes the top-level cache: block and the GOCACHE/GOMODCACHE env vars, which is a bit wider than the title suggests. My guess is those vars never took effect under the old list syntax (same bug as GOOS), so ~/gocache/~/gomodcache were never populated and the caching was effectively a no-op. Is the intent to drop Go build/module caching for good, or is wiring it back up with the mapping syntax a follow-up?