Removing problem introduced by searching the configmap name again

[gralfca]

Looking for the configmap again inside the container update function introduces an error because all env vars corresponding to configmaps that didn't change are updated as well to the value of the config map that actually changed.

Consider a deployment object with a container in which configmap.fabric8.io/update-on-change = cm1,cm2

Then modify cm1, and then modify cm2. in the end both FABRIC8_CM1_CONFIGMAP and FABRIC8_CM2_CONFIGMAP could be set to the value of cm2.