Crop calendar input file error in coupled case

### Brief summary of bug

Jim Edwards (@jedwards4b) reported an error in a fully-coupled case that seems to have something to do with reading the GDD20 baseline file (`stream_fldFileName_gdd20_baseline`). This happens with the run start date set to 2001-12-30, but not with it set to 0001-01-01.

I don't think this reproduces in stand-alone CTSM; we happen to have a few `CLM60%BGC-CROP` tests that start on 2001-12-30, and they seem to work fine. E.g., `ERP_D.f10_f10_mg37.IHistClm60Bgc.derecho_gnu.clm-decStart`.

Jim reports that this is not a blocker, and he doesn't need it resolved, so I've marked it as low priority. But it sure is weird!

### General bug information

**CTSM version you are using:** ctsm5.3.029

**Does this bug cause significantly incorrect results in the model's science?** Unknown

**Configurations affected:** Unknown

### Details of bug

It seems like it has to do with this check:
https://github.com/ESCOMP/CTSM/blob/be65fad30a741fc594bca9e1221ffe987e7bf271/src/cpl/share_esmf/cropcalStreamMod.F90#L460-L465

See log output below for more info.

### Important output or errors that show the problem
Log files are copied to my home directory at `/glade/u/home/samrabin/jim_cropcal_issue/`.

`cesm.log.9096833.desched1.250407-094151`:
```
dec2393.hsn.de.hpc.ucar.edu 239: (dshr_fldbun_GetFldPtr): ERROR field gdd20bl_56
dec2393.hsn.de.hpc.ucar.edu 239:
dec2393.hsn.de.hpc.ucar.edu 239: ESMF_Finalize: Error closing trace stream
dec2393.hsn.de.hpc.ucar.edu 239: MPICH ERROR [Rank 239] [job id 7726a0d8-a3b1-4410-b15c-e85261afa55a] [Mon Apr 7 09:46:26 2025] [dec2393] - Abort(1) (rank 239 in comm 496): application called MPI_Abort(comm=0x84000001, 1) - process 239
```

The `gdd20bl_56` variable (and `gdd20bl_58`, which a different PET log file complained about) does exist and hasn't caused problems for us before.

The PET log file, `PET0239.ESMF_LogFile`, cites the line in question:
```
20250407 094626.267 ERROR PET0239 (dshr_fldbun_GetFldPtr): ERROR field gdd20bl_56 333^W351\R> not in FB
20250407 094626.269 ERROR PET0239 dshr_strdata_mod.F90:1193 Failure - Passing error in return code
20250407 094626.269 ERROR PET0239 cropcalStreamMod.F90:462 Failure - Passing error in return code
20250407 094626.269 INFO PET0239 Finalizing ESMF with endflag==ESMF_END_ABORT
20250407 094626.269 ERROR PET0239 /glade/derecho/scratch/csgteam/temp/spack/derecho/24.12/builds/spack-stage-esmf-8.8.0-ypx5ao4unezqxatt7vhrq5cyvrcn67xv/spack-src/src/Infrastructure/Trace/src/ESMCI_Trace.C:1816 ESMCI::TraceEventRegionExit() Wrong argument specified - Trace regions not properly nested exiting from region: [ESMF] Expected exit from: cropcaldyn_strd_adv_tint
20250407 094626.269 ERROR PET0239 /glade/derecho/scratch/csgteam/temp/spack/derecho/24.12/builds/spack-stage-esmf-8.8.0-ypx5ao4unezqxatt7vhrq5cyvrcn67xv/spack-src/src/Infrastructure/Trace/src/ESMCI_Trace.C:1258 ESMCI::TraceClose() Wrong argument specified - Internal subroutine call returned Error
20250407 094626.269 ERROR PET0239 ESMF_Trace.F90:102 ESMF_TraceClose() Wrong argument specified - Internal subroutine call returned Error
```