Multi master deployments for k8s driver use different service account
keys for each api/controller manager server which leads to 401 errors
for service accounts. This patch will create a signed cert and private
key for k8s service account keys explicitly, dedicatedly for the k8s
cluster to avoid the inconsistent keys issue.
Task: 21653
Story: 1766546
Change-Id: I61547405f866d3c5a84da63de66724b55af1066a