We're often contacting the K8s API through a loadbalancer (e.g. Octavia
LB in DevStack deployments, HAProxy in OpenShift) and we've often seen
they're able to drop connections silently, effectively leaving our
requests hanging forever. This got fixed in `K8sClient.watch` which
helped a lot, but we now seem to see it happening with other requests.
In order to make sure we won't block processing events for a resource
forever due to that, this commit adds read timeout to all the methods in
K8sClient.
Closes-Bug: 1897893
Change-Id: If1846ec78abc0840e7aba04565b220a1d20e5dc9