x/build: add darwin-arm64-14 and darwin-arm64-15 builders

[prattmic]

[gopherbot]

Change https://go.dev/cl/665895 mentions this issue: main.star: add darwin-arm64_14 and darwin-arm64_15 builders

[gabyhelp]

Related Issues

• x/sys: add darwin/arm support #10813 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[gopherbot]

Change https://go.dev/cl/665915 mentions this issue: cmd/makemac: add darwin-arm64-14 and darwin-arm64-15

[gopherbot]

Change https://go.dev/cl/666175 mentions this issue: main.star: remove darwin-arm64_14 and darwin-arm64_15 known issues

[gopherbot]

Closed by merging CL 666175 (commit golang/build@6c6b9fe) to luci-config.