Add metric to track failed layer pull by registry-facade

[sagor999]

Is your feature request related to a problem? Please describe

We don't have a metric that tracks if registry-facade is failing to pull an image.
It can happen if there is some connectivity issue to registry or due to some other errors.
If would be a good idea to track this and have alerts in place.

Code to add this into:

gitpod/components/registry-facade/pkg/registry/metrics.go

Line 34 in 47972ee

resp, err := m.delegate.RoundTrip(req)

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