Unclear numbering logic for restart_step and check_step

[castelletto1]

The numbering logic for restart_step and check_step is unclear. For example, for the ContactMechanics_SimpleCubes smoke test (here) they are set to 10 and 20, respectively:

https://github.com/GEOS-DEV/integratedTests/blob/402c5a9f7ab2f3c5f123603c9db93e3feed51c12/tests/allTests/contactMechanics/contactMechanics.ats#L10-L15

However, the simulation runs for 10 cycles, ranging from 0 to 9 -- performing 11 time steps due to a time step cut. It produces three restart files:

• ContactMechanics_SimpleCubes_smoke_restart_000000000.root
• ContactMechanics_SimpleCubes_smoke_restart_000000005.root
• ContactMechanics_SimpleCubes_smoke_restart_000000010.root

It is confusing what 10 and 20 stand for.