Use unmodified PeriodSeconds setting

[manigandham]

Use actual interval setting from readiness probe instead of modifying.

Fix #1213

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[k8s-reviewable]

This change is 

[manigandham]

CLA signed

[coveralls]

Coverage increased (+0.03%) to 44.463% when pulling ac9f960 on manigandham:master into 31d45d8 on kubernetes:master.

[nicksardo]

This is by design. The GCP health check isn't supposed to be a 1:1 check with the readiness probe. The health checks are for the nodes, not the pods. Adding the 60 seconds prevents the GCP health checks from overwhelming the containers if the number of nodes greatly out pods.

[manigandham]

Ah ok, makes sense. Thanks for the info.