Fix #2439, UT updates for alternate time configuration

[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 time unit tests are broken if CFE_PLATFORM_TIME_CFG_SRC_MET is set to true #2439
  • Applies the same updates Jake made in Fix #2090, UT updates for alternate time configuration #2099 to the GPS and MET tests in order to get the CI green again

Testing performed
GitHub CI actions all passing successfully (incl. Build + Run, Unit/Functional Tests etc.).
Tested locally to confirm cFS builds without error and tests passing for all 3 external time source options:

• CFE_PLATFORM_TIME_CFG_SRC_MET
• CFE_PLATFORM_TIME_CFG_SRC_GPS
• CFE_PLATFORM_TIME_CFG_SRC_TIME

Expected behavior changes
No change to code - test updates only.

System(s) tested on
Debian GNU/Linux 12 (bookworm)
Current main branch of cFS bundle.

Contributor Info
Avi Weiss   @thnkslprpt