Update go-infra: detect VERSION or go/VERSION

[dagood]

• Update go-infra to get this change: Let the outer repo provide VERSION go-infra#22
• Now that it's handled in go-infra, undo Find submodule VERSION file for build asset json #390

When we changed to submodules, I changed eng/pipeline/rolling-internal-pipeline.yml to point at go/VERSION rather than VERSION. Updating the file detection in microsoft/go rather than microsoft/go-infra was a quick fix.

However, the boring branches don't have VERSION files. This means in the build asset JSON files, boring builds have the default main-1 value in them, because there's no version info. So, auto-update into microsoft/go-images isn't working.

To fix this, I changed go-infra to first check VERSION (in our repo) then go/VERSION (the submodule). (microsoft/go-infra#22) This means we can undo the eng/pipeline/rolling-internal-pipeline.yml change. In the boring branches, we can check in our own VERSION file to make auto-update work.

We probably also need a VERSION file to exist in the boring branches for some future work:

• Include Go version in name of artifact (tar.gz, zip) #140
• go version should inform that the go binary is generated by microsoft  #262