Manage mover model warnings in example and validation models

[hcasperfu]

The models under Fluid.Movers have a number of warnings to alert the user when the model is configured in ways that are acceptable but not optimal. This ensures such configurations are indeed intended and the assumptions and dangers are understood and accepted.
This issue is to manage the warning messages in our own example and validation models in order to reduce confusion.

[hcasperfu]

This is fixed in #3845 for maint_11.x and will be included in #3834 for master.