Don't use a custom dialer for the kubelet if is not rotating
certificates, so we can reuse TCP connections because we don't need
a customer dialer.
Kubelet needs to be able to recover from stale http connections.
HTTP2 has a mechanism to detect broken connections by sending periodical pings.
HTTP1 only can have one persistent connection, and it will close all Idle connections
once the Kubelet heartbet fails. However, since there are many edge cases that we can't
control, users can still opt-in to the previous behavior for closing the connections by
setting the environment variable DISABLE_HTTP2.
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