Expanding the list of ELM-FATES tests to include in the nightly test runs

[glemieux]

Per discussion with @peterdschwartz @rgknox and myself in #6639 (comment):

But these tests (or at least a representative sample) should eventually make it into the nightly testing to ensure ELM only changes do not break compatibility with FATES. You all have done a pretty good job of laying the groundwork for the test coverage, and I have been assuming (hoping given how prominent FATES is becoming in ELM) that they will be included in our test suites when the features are ready.

💯 agree. I think planning for the staged inclusion of more fates tests into the nightly is something that I would ask for guidance on from @jenniferholm and @rgknox based on the current and future E3SM land phase plans. I'll fire up a discussion thread on this issue.

Currently, the fates development team has a larger number of testmods than is currently exercised in nightly tests via the e3sm_land_developer test suite. These additional tests are available to be exercised as part of the fates development process itself for fates-side pull requests and a manually run on an as needed basis. The question up for discussion is should we develop a plan for migrating more of the fates tests into the automatic testing via e3sm_land_developer or another suite?

[glemieux]

FATES version of this discussion here: NGEET/fates#1284