[receiver/k8scluster] Deprecate k8s.container.restarts in favor of k8s.container.restart_count

[povilasv]

Description:

Deprecate k8s.container.restarts in favour of k8s.container.restart_count with proper units. As described in
#10553

Link to tracking Issue:

#10553

Testing:

• Updated existing tests

Documentation:

• Updated

[dmitryax]

Let's not introduce any new metric because of this. We can fix the units by one feature gate for all the metrics. But before that, I'd suggest move all the metrics to mdatagen keeping the current units

[povilasv]

Closing this as we don't want to change the metric name here, the plan is to introduce feature gate for renames