In hybrid runs, MARBL initializes from IC file rather than restart file

[mnlevy1981]

@kristenkrumhardt set up a hybrid run with MARBL tracers and noticed discontinuities in those tracers between the last month of the ref case and the first month of the hybrid. @klindsay28 noticed the ideal age tracers were initializing from restart as expected, and we compared the initialization process of the two passive tracer modules.

To fix this, we need a new logical variable in the MARBL control structure (MARBL_TRACERS_IC_FILE_IS_Z); the default will be .true. but it should be set to .false. when $RUN_TYPE == "hybrid" and $CONTINUE_RUN == False. We then need to mimic this block of code from ideal_age_example.F90:

if (CS%Z_IC_file) then
  OK = tracer_Z_init(CS%tr(:,:,:,m), h, CS%IC_file, name,&
                     G, GV, US, -1e34, 0.0) ! CS%land_val(m))
  if (.not.OK) then
    OK = tracer_Z_init(CS%tr(:,:,:,m), h, CS%IC_file, &
             trim(name), G, GV, US, -1e34, 0.0) ! CS%land_val(m))
    if (.not.OK) call MOM_error(FATAL,"initialize_ideal_age_tracer: "//&
            "Unable to read "//trim(name)//" from "//&
            trim(CS%IC_file)//".")
  endif
else
  call MOM_read_data(CS%IC_file, trim(name), CS%tr(:,:,:,m), G%Domain)
endif

but continue to use MOM_initialize_tracer_from_Z rather than tracer_Z_init.

The last step will be to update the default value for MARBL_TRACERS_IC_FILE in MOM_interface to include

$RUN_TYPE == "hybrid" and $CONTINUE_RUN == False:
    = f'./{$RUN_REFCASE}.mom6.r.{$RUN_REFDATE}-{$RUN_REFTOD}.nc'

in a way that takes precedence over the existing checks that set it to ecosys_jan_IC_omip_latlon_1x1_180W_c231221.nc

[mnlevy1981]

After further discussion, I think the best option would be to have a variable MARBL_INIT_FROM_REST_FILE that depends on RUN_TYPE (default is .false. for startup and .true. for hybrid and branch); we would then want MARBL_TRACERS_IC_FILE to depend on this new variable.

@alperaltuntas RUN_TYPE is in env_run.xml, so this new MARBL_INIT_FROM_REST_FILE would need to be in MOM_input.yaml; does ParamGen support other variables in MOM_input.yaml depending on it?