Add tests to test suite to run run_tower

Rather than pursue #2276 I think we should add a system test that runs a run_tower to setup and run a few cases under run_tower so we know it's working. This will also help with making sure that externals updates don't break run_tower as we saw in #2437. And as discussed here: https://github.com/ESCOMP/CTSM/issues/2437#issuecomment-2018895095 we should add this to the prealpha test list so that new externals updates will be tested with CESM alpha tags and we can find problems sooner.

(Updated Jul/23/2026 to say run_tower rather than run_neon)