CI: restore Go integ tests

[justinmk3]

Problem

#3551 switched the integ tests CodeBuild CI spec to run tests as unprivileged (non-root) user, in part to fix #3550 .

But the goenv and go commands fail now, and had to be disabled:

        # Install latest version of Go (known to 'goenv')
        # - eval "$(goenv init -)"
        # - 'export PATH="$GOROOT/bin:$PATH:$GOPATH/bin"'
        # - '>/dev/null VERSION=$(goenv install --list | tail -n 1) && 2>/dev/null goenv install $VERSION'
        # - '>/dev/null goenv global $VERSION && go env -w GOPROXY=direct'
        # - go version

Expectation

Restore use of go in the integ tests and re-enable the tests disabled in fab07b3