Remove redundant Resource.Empty fallback in GetResource() calls

[rajkumar-rangaraj]

Fixes ##3646 (comment)
Design discussion issue #

Changes

Please provide a brief description of the changes here.

Removed the redundant ?? Resource.Empty null-coalescing and ?. null-conditional operators when calling GetResource() on ParentProvider in:

• GenevaLogExporter.cs
• GenevaTraceExporter.cs

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• [ ] Unit tests added/updated
• [ ] Appropriate CHANGELOG.md files updated for non-trivial changes
• [ ] Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.91%. Comparing base (e15516e) to head (3aeb5b4).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3806      +/-   ##
==========================================
+ Coverage   71.87%   71.91%   +0.04%     
==========================================
  Files         457      447      -10     
  Lines       17843    17792      -51     
==========================================
- Hits        12825    12796      -29     
+ Misses       5018     4996      -22     

Flag	Coverage Δ
unittests-Exporter.Geneva	54.15% <100.00%> (-0.33%)	⬇️
unittests-Instrumentation.Cassandra	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...OpenTelemetry.Exporter.Geneva/GenevaLogExporter.cs	90.38% <100.00%> (ø)
...enTelemetry.Exporter.Geneva/GenevaTraceExporter.cs	86.04% <100.00%> (ø)

... and 11 files with indirect coverage changes

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