Fix #1929, Remove redundant status check in CFE_ES_RegisterCDSEx()

[thnkslprpt]

Checklist

• 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 ES missing branch in CFE_ES_RegisterCDSEx, overwrite success check doesn't make sense #1929
  • Additional status check was made redundant with the changes here in Fix #943, #924 and #502, improve resource ID management #946

Testing performed
GitHub CI actions all passing successfully (incl. Build + Run, Unit/Functional Tests etc.).
This PR (slightly) increases coverage by one branch by removing an unreachable branch.

Expected behavior changes
No change to behavior.

Contributor Info
Avi Weiss @thnkslprpt