Automatic merge from submit-queue (batch tested with PRs 60696, 60876, 60901, 60925, 60428). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
client-go/util/cert go_library shouldn't depend on testdata
**What this PR does / why we need it**: 981dd8dc66 (diff-eb996d3ca3a215d7d93faaaffb77dbd7) accidentally added a testdata dependency on the go_library rule, rather than the go_test. This breaks vendoring of this rule into other bazel projects that prune out tests and testdata.
Only the unit test depends on testdata, so the BUILD file should reflect that, too.
x-ref https://github.com/kubernetes/test-infra/pull/6835#discussion_r173010769
**Release note**:
```release-note
NONE
```
cc @BenTheElder @krzyzacy
External Repository Staging Area
This directory is the staging area for packages that have been split to their own repository. The content here will be periodically published to respective top-level k8s.io repositories.
Repositories currently staged here:
k8s.io/apiextensions-apiserverk8s.io/apik8s.io/apimachineryk8s.io/apiserverk8s.io/client-gok8s.io/kube-aggregatork8s.io/code-generatork8s.io/metricsk8s.io/sample-apiserverk8s.io/sample-controller
The code in the staging/ directory is authoritative, i.e. the only copy of the code. You can directly modify such code.
Using staged repositories from Kubernetes code
Kubernetes code uses the repositories in this directory via symlinks in the
vendor/k8s.io directory into this staging area. For example, when
Kubernetes code imports a package from the k8s.io/client-go repository, that
import is resolved to staging/src/k8s.io/client-go relative to the project
root:
// pkg/example/some_code.go
package example
import (
"k8s.io/client-go/dynamic" // resolves to staging/src/k8s.io/client-go/dynamic
)
Once the change-over to external repositories is complete, these repositories
will actually be vendored from k8s.io/<package-name>.