No feedback in the UI when cluster creation in GKE fails

Description

Cluster creation in GKE can fail because of many reasons. Network limits is one of them probably.

Currently there is no feedback in the UI when it happens. I see in the console that cluster creation failed, but in GitLab I still see

Kubernetes cluster is being created on Google Kubernetes Engine...

Proposal

Show some meaningful error.

/cc @danielgruesso @DylanGriffith @tkuah