Remove secrets from vendor kubernetes test files

[atantawi]

commit vendored in some GCP BASE64 known secrets in https://github.com/ibm/kube-safe-scheduler

Found verified result 🐷🔑
Detector Type: GCP
Decoder Type: BASE64
Raw result: image-pulling@authenticated-image-pulling.iam.gserviceaccount.com
File: vendor/k8s.io/kubernetes/test/e2e/common/runtime.go
Timestamp: 2019-05-03 17:14:05 -0400 -0400
Line: 251
Link: https://github.com/ibm/kube-safe-scheduler/blob/15bd56e95b439420b32817ff04433c697a066e01/vendor/k8s.io/kubernetes/test/e2e/common/runtime.go
Repository: https://github.com/ibm/kube-safe-scheduler.git
Commit: 15bd56e

Found verified result 🐷🔑
Detector Type: GCP
Decoder Type: BASE64
Raw result: image-pulling@authenticated-image-pulling.iam.gserviceaccount.com
File: vendor/k8s.io/kubernetes/test/e2e_node/runtime_conformance_test.go
Timestamp: 2019-05-03 17:14:05 -0400 -0400
Line: 52
Link: https://github.com/ibm/kube-safe-scheduler/blob/15bd56e95b439420b32817ff04433c697a066e01/vendor/k8s.io/kubernetes/test/e2e_node/runtime_conformance_test.go
Repository: https://github.com/ibm/kube-safe-scheduler.git
Commit: 15bd56e

[atantawi]

Delete following files from vendor directory:

1. vendor/k8s.io/kubernetes/test/e2e/common/runtime.go
2. vendor/k8s.io/kubernetes/test/e2e_node/runtime_conformance_test.go

Add note in readme for users to download such files in forked repository.