add "Timeout" option and retry for function `runKubectl`

# Summary

add "Timeout" option and retry for function `runKubectl`.

## Use Cases

1. If the apiserver is unreachable for some reason, `runKubectl` will hang. We need to set a reasonable timeout and retry after few seconds.

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**Message from the maintainers**:

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Locate the Go function runKubectl and inspect how it invokes kubectl and handles command completion. Define a reasonable timeout and retry behavior for an unreachable apiserver, then verify that normal commands still complete and that timeout failures are retried as intended.

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