InitializeFlags carries over glog flags with new defaults, and makes `flag.Parsed()` to return true.

NewProbeCmd creates the cobra.Command for the probe command.

DefaultCSRGracePeriodPercentage is the default length of certificate rotation grace period, configured as the percentage of the certificate TTL.

DefaultCSRInitialRetrialInterval is the default initial interval between retries to send CSR to upstream CA.

DefaultCSRMaxRetries is the default value of CSR retries for Citadel to send CSR to upstream CA.

DefaultMaxWorkloadCertTTL is the default max TTL of issued workload certificates.

DefaultProbeCheckInterval is the default interval of checking the liveness of the CA.

DefaultRequestedCACertTTL is the default requested TTL for the workload.

DefaultSelfSignedCACertTTL is the default TTL of self-signed CA root certificate.

DefaultWorkloadCertGracePeriodRatio is the default length of certificate rotation grace period, configured as the ratio of the certificate TTL.

DefaultWorkloadCertTTL is the default TTL of issued workload certificates.

DefaultWorkloadMinCertGracePeriod is the default minimum grace period for workload cert rotation.

ListenedNamespaceKey is the key for the environment variable that specifies the namespace.