Undo API-breaking change to go_sdk experiments attribute (#4210)

**What type of PR is this?**

Bug fix, see
https://github.com/bazel-contrib/rules_go/pull/4022#issuecomment-2566548860

**What does this PR do? Why is it needed?**

Reverts the behavior to the API while keeping the optimization

**Which issues(s) does this PR fix?**

Fixes #

**Other notes for review**
2 files changed