`pure` has no effect when `goarch` and `goos` are `auto`

### What version of rules_go are you using?

`v0.29.0`

### What version of gazelle are you using?

`v0.24.0`

### What version of Bazel are you using?

`4.2.2`

### Does this issue reproduce with the latest releases of all the above?

Yes.

### What operating system and processor architecture are you using?

linux x86_64 and macos x86_64.

### Any other potentially useful information about your toolchain?

None.

### What did you do?

Configure the `pure` attribute on a `go_binary` target where `goarch` and `goos` are `auto`.

### What did you expect to see?

It should have an effect.

### What did you see instead?

It does not have an effect.

---

See [this repository](https://github.com/uhthomas/rules_go-issue-3033) for a full reproduction and explanation.

Start with the linked rules_go-issue-3033 reproduction and compare a go_binary target using pure with goarch and goos set to auto. Trace the rules_go handling of those attributes and verify the completed change makes pure affect the target on the listed Linux and macOS x86_64 environments.

Written by the indexing model from the issue text.