fix(FormGroupContainer): only apply hover styles if onClick
fix(FormGroupContainer): only apply hover styles if onClick

This was is fixing a regression from 5e2d832 which caused
hover on all FormGroupContainers. Now it will only apply the
outline and cursor pointer when a onClick prop is provided.
Currently, this only occurs for container pods when creating
a service.

Closes DCOS-18317

dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui,dcos/dcos-ui