Automatic merge from submit-queue (batch tested with PRs 50087, 39587, 50042, 50241, 49914)
Add node e2e test for Docker's shared PID namespace
Ref: https://github.com/kubernetes/kubernetes/issues/42926
This PR adds a simple test for the shared PID namespace that's enabled when Docker is 1.13.1+.
/sig node
/area node-e2e
/assign @yujuhong
**Release note**:
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