fix: LoggingSpanExporter and LoggingMetricExporter flush() always returns success

[ADITYA-CODE-SOURCE]

Fixes a bug where LoggingSpanExporter.flush() and LoggingMetricExporter.flush() unconditionally returned success, even if underlying logger handlers failed during flushing. This masked errors from the caller.

Changes

• Modified LoggingSpanExporter.flush() to return the actual result code instead of calling .succeed() at the end.
• Applied the same fix to LoggingMetricExporter.flush().

Fixes #8360

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ADITYA-CODE-SOURCE / name: ADITYA-CODE-SOURCE (7195477, 7454852, be535cb)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.83%. Comparing base (1b207c6) to head (7195477).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8361      +/-   ##
============================================
+ Coverage     90.82%   90.83%   +0.01%     
  Complexity     7927     7927              
============================================
  Files           895      895              
  Lines         23872    23870       -2     
  Branches       2378     2376       -2     
============================================
+ Hits          21681    21683       +2     
+ Misses         1446     1442       -4     
  Partials        745      745              

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