Shorten or Replace zdplaskin_ex3 Test

[smpeyres]

This test is simply way too long for a test. Should be a replaced by a shorter version that runs in a fraction of the time or several mini-tests. A better place for this would be as a tutorial.

[cticenhour]

Not being more familiar with this particular test, I have a couple thoughts (forgive if preaching to the choir 😄):

• Shorten the end time using cli_args to get the length you want, keeping in mine the time necessary to get the capability testing you need.
• If the desired capability if happening later in the test, consider using the checkpoint system to perform the first bit of the simulation offline and then use it to seed all future tests, keeping the test runtime shorter while getting the full timeframe desired for simulation.