This fonts are pretty cool. But I don't understand why they just used Roboto or Noto fonts.
As these fonts are purportedly intended for testing purposes, presumably they will be included in the package. Adding additional licenses to the codebase complicates the usage. You might agree to the terms of the Go license, but not the Apache license, for instance.
Since this new font is licensed under the Go license, there is only one set of terms you need to agree to. This is a much better situation for many reasons.
Also, considering that Google owns Noto and has relicensed it in the recent past, it would probably be possible for them to ship it under the Go license too.
Not really if the additional licensed parts are tests. Most things don't ship their dependencies' tests in the final binary.