Update vendoring for Gitaly

This is necessary since we're depricating old RPC naming scheme gitaly!219 (merged)

Only things I updates:

+ v  gitlab.com/gitlab-org/gitaly-proto/go                          v0.17.0  v0.17.0
- v  gitlab.com/gitlab-org/gitaly-proto/go                          v0.14.0  v0.14.0
- vt gitlab.com/gitlab-org/gitaly-proto/go/helper                            
+ v  gitlab.com/gitlab-org/gitaly/auth                              v0.21.2  v0.21.2
- v  gitlab.com/gitlab-org/gitaly/auth                              v0.14.0  v0.14.0
+ v  gitlab.com/gitlab-org/gitaly/client                            v0.21.2  v0.21.2
- v  gitlab.com/gitlab-org/gitaly/client                            v0.14.0  v0.14.0
+ v  gitlab.com/gitlab-org/gitaly/streamio                          v0.21.2  v0.21.2

Related Issue gitaly#381 (closed)