Stop using github.com/pkg/errors

[Ivan Dimitrov]

How to categorize this issue?

/kind enhancement
/priority 3
/platform gcp

What would you like to be added:
Similar to gardener/gardener#4280 we should be using Go native error wrapping (available since GO 1.13).

$ rg '"github.com/pkg/errors"' | grep -v vendor/ | cut -f 1 -d ':' | cut -d '/' -f 1-3 | sort | uniq -c | sort
      1 pkg/apis/gcp
      1 pkg/controller/controlplane
      1 pkg/controller/infrastructure
      1 pkg/webhook/controlplaneexposure
      1 test/tm/generator.go
      3 pkg/controller/worker

Why is this needed:
Getting rid of vendors in favor of using stdlib is always nice. Others seem to do this as well - kubernetes/kubernetes#103043 and containerd/console#54.