[golang] restrict access to golang issues (#11663)

We've had multiple security reports originating from crashes discovered
by oss-fuzz. I was unaware that the results were entirely public.

Restrict access to issues to the Go Security team.

**Note:** It's unclear to me if this actually accomplishes what I want.
`view_restrictions` seems entirely undocumented. From contextual clues
from other projects it _seems_ that removing the field causes
restriction, but that is entirely a guess.

Author: rolandshoemaker

projects/golang/project.yaml

@@ -1,13 +1,13 @@
 homepage: "https://golang.org/"
 main_repo: "https://github.com/golang/go"
-primary_contact: "[email protected]"
+primary_contact: "[email protected]"
 auto_ccs:
- - "[email protected]"
+ - "[email protected]"
+ - "[email protected]"
+ - "[email protected]"
  - "[email protected]"
- - "[email protected]"
 language: go
 sanitizers:
  - address
 fuzzing_engines:
  - libfuzzer
-view_restrictions: none