Merge pull request #36592 from andrewsykim/36273-set-all-node-conditions-unknown-when-node-unreachable

Automatic merge from submit-queue (batch tested with PRs 40917, 41181, 41123, 36592, 41183)

Set all node conditions to Unknown when node is unreachable

**What this PR does / why we need it**:
Sets all node conditions to Unknown when node does not report status/unreachable

**Which issue this PR fixes** 
fixes https://github.com/kubernetes/kubernetes/issues/36273