Fix #1448, Simplify and clarify EVS_AddLog logic

[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 Simplify LogOverflowCounter increment logic #1448
  • Removes duplication of incrementing the LogOverflowCounter
  • Simplifies the function and makes logical flow a little clearer

Testing performed
GitHub CI actions all passing successfully.

Would be good to add functional tests for this in the future - I noticed that changing the second block to just a simple else also passes all the coverage tests.

Expected behavior changes
No change.

Contributor Info
Avi Weiss @thnkslprpt

[thnkslprpt]

I can also update to the more terse version if there is a general desire to move in that direction as updates are made:

if (CFE_EVS_Global.EVS_LogPtr->LogFullFlag)
...
if ((!CFE_EVS_Global.EVS_LogPtr->LogFullFlag) ||
...

Side note - LogFullFlag is actually not a bool type - although it's treated as such.

Works fine obviously, but I think I'll open a new issue about it - just checking if there are any other similar cases first (ints being treated as bools). Probably left over from earlier times before bool was commonly used.