Fix #416, cleanup cf unused error codes

[avan989]

Fix #416, clean up cf_cfdp_s.c for unused error code and update unit test

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fixes #416 clean up unused error code and update unit test

Testing performed
Steps taken to test the contribution:

1. Make SIMULATION=native install

2. upload and download using COSMOS ground system

3. Make SIMULATION=native ENABLE_UNIT_TESTS=true prep

4. make -j

5. make test

6. make lcov

Expected behavior changes
no impact to behavior. error code as always unused.

System(s) tested on

• ubuntu 22.04

Third party code
If included, identify any third party code and provide text file of license

Contributor Info - All information REQUIRED for consideration of pull request
Full name and company/organization/center of all contributors ("Personal" if individual work)

• Note CLA's apply to software contributions.

Anh Van, GSFC