Remove thermomechanics from Serac driver and remove default.lua

[white238]

Test PR: LLNL/serac_tests#24 (merged to main)

thermomechanics was not working in default.lua and after speaking to @btalamini this class needs to be fixed anyways. I found this input file named confusing and this should alleviate that.

I also removed the ability to use anything other than solid and heat_transfer separately in the driver.

Fixes #1250

[chapman39]

should we also remove data/input_files/tests/thermal_solid/thermal_expansion.lua or fix that at some point in the future?

[white238]

This PR was aimed at unblocking a user to ran into this. We should have a followup discussion on what path to take to re-enable input files with thermomechanics and also traction. As well as the thermomechanics class can't handle differing order's between the solid and heat_transfer parts.

[white238]

This PR was aimed at unblocking a user to ran into this. We should have a followup discussion on what path to take to re-enable input files with thermomechanics and also traction. As well as the thermomechanics class can't handle differing order's between the solid and heat_transfer parts.

Made an issue #1256