Switch order of test and check-generated

[hiddeco]

As test modifies go.mod and check-generated restores it,
ultimately restoring the git state to a clean working tree.

This is a hotfix as bin/helm/update_codegen.sh has only a limited
lifetime left in this repository.

#2344 follow up.

[squaremo]

This is 👍 for unblocking CI. We ought to figure out (if it's still a problem in fluxcd/helm-operator) how to remove the ordering dependency, as a follow-up. (We should probably also use -mod=readonly to make things fail if they need to modify go.mod).

[hiddeco]

Found the recipe to replicate the modification to go.mod locally:

$ GOPATH=/tmp make check-generated
$ GOPATH=/tmp make test
$ git diff go.mod
      1 diff --git a/go.mod b/go.mod
      2 index e76fb198..72a523f5 100644
      3 --- a/go.mod
      4 +++ b/go.mod
      5 @@ -22,6 +22,7 @@ require (
      6         github.com/go-logfmt/logfmt v0.4.0 // indirect
      7         github.com/gobwas/glob v0.2.3 // indirect
      8         github.com/gogo/googleapis v1.2.0 // indirect
      9 +       github.com/gogo/protobuf v1.2.1
     10         github.com/gogo/status v1.1.0 // indirect
     11         github.com/golang/gddo v0.0.0-20190312205958-5a2505f3dbf0
     12         github.com/golang/groupcache v0.0.0-20190129154638-5b532d6fd5e // indirect
     13 @@ -66,6 +67,7 @@ require (
     14         golang.org/x/oauth2 v0.0.0-20190402181905-9f3314589c9a // indirect
     15         golang.org/x/sys v0.0.0-20190616124812-15dcb6c0061f
     16         golang.org/x/time v0.0.0-20190308202827-9d24e82272b4
     17 +       gonum.org/v1/gonum v0.0.0-20190808205415-ced62fe5104b
     18         google.golang.org/api v0.3.2 // indirect
     19         google.golang.org/appengine v1.5.0 // indirect
     20         google.golang.org/grpc v1.20.0 // indirect