CI simplifications

[baperry2]

We rebuild PelePhysics over and over in the CI to test various different mechanisms, EOS, and Transport models. We can be more efficient by building AMReX as a library once and linking to it, instead of rebuilding all the AMReX stuff every time we rebuild PelePhysics.

In addition, this PR makes a few changes to promote faster results in the CI:

• Don't run the free disk space script, which takes a nontrivial amount of time and doesn't seem to be necessary
• Move some stuff specific to the Jacobian test from the dependencies section to get to actual tests faster

TODO:

• @jrood-nrel : right now the AMReX build (as well as the Sundials build) don't use ccache, perhaps they could benefit from that as well?
• There are some errors in the ReactEval case, which I converted from 3D to 2D to only have to use one version of AMReX. That shouldn't affect the results, so more investigation is needed here