Fix trace kIsSampled flag set incorrectly

[luyor]

Fixes trace_flags.kIsSampled is set to true if sample_results.desicion!=DROP, but it should be true only if sample_results.desicion==RECORD_AND_SAMPLE.

Similar logic can be found in golang opentelemetry sdk: https://github.com/open-telemetry/opentelemetry-go/blob/ef6c0da0de3b39c20a753354446807d7577aca61/sdk/trace/tracer.go#L104

Changes

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[linux-foundation-easycla]

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• ✅ login: luyor (528dd1f)

[codecov]

Codecov Report

Merging #1465 (071bdbf) into main (7b0bb14) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1465      +/-   ##
==========================================
+ Coverage   85.30%   85.31%   +0.02%     
==========================================
  Files         154      154              
  Lines        4374     4377       +3     
==========================================
+ Hits         3731     3734       +3     
  Misses        643      643              

Impacted Files	Coverage Δ
sdk/include/opentelemetry/sdk/trace/sampler.h	100.00% <100.00%> (ø)
sdk/src/trace/tracer.cc	90.25% <100.00%> (ø)

[lalitb]

Thanks for the fix. LGTM, can you fix the format to enable CI to pass - https://github.com/open-telemetry/opentelemetry-cpp/blob/main/CONTRIBUTING.md#how-to-send-pull-requests

[luyor]

Thanks for the fix. LGTM, can you fix the format to enable CI to pass - https://github.com/open-telemetry/opentelemetry-cpp/blob/main/CONTRIBUTING.md#how-to-send-pull-requests

Format is fixed. Thanks for reviewing.