Clear lookup function cache between chart installs

[mattfarina]

The lookup function appears to cache data. This is a problem. For example, you have rancher-monitoring as a chart that depends on rancher-monitoring-crd for the CRDs. When you install rancher-monitoring it sees the CRD chart isn't installed so it installs it. Then, in the rancher-monitoring chart it uses the lookup function to see if the CRDs are installed. In between the install of the two charts the underlying cache isn't cleared so the lookup function will not return their existence in the cluster.

In between the installation of different charts the lookup function needs to have its cache cleared.