Make the helper Pod timeout configurable

[mgoltzsche]

...because depending on the helper Pod a different timeout may be needed.

My use case is cache-provisioner that requires the helper Pod to synchronize the volume contents with an image registry which may take more than the hardcoded timeout of 2 minutes.

[daicang]

Sometimes when load is high, helper pod takes > 2min to create, which cases infinite timeout when creating PV. We enlarged timeout from 2min to 4min and problem solved.