[SDK] Swap Tracer/Meter/LoggerConfig disabled for enabled

[AyushMukkanwar]

Fixes #3867

Changes

Replaced the private disabled_ members in TracerConfig, MeterConfig and LoggerConfig with enabled_ to avoid double-negative configuration patterns, aligning with OpenTelemetry Specification 4823.

The public configuration APIs Enabled(), Disabled(), and IsEnabled() remain fully backwards-compatible, while the class constructors were updated to default enabled=true.

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

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added (Existing tests verify functionality via public API)
• Changes in public API reviewed

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: marcalff / name: Marc Alff (f8e1d91)

[marcalff]

Please remove the links to private files in the change set comments, like cci:2://file:///home/ayush_mukkanwar/Dev/OSS/opentelemetry-cpp/sdk/test/trace/tracer_config_test.cc:76:0-78:2

No need to link to a file name and line number, just TracerConfig is enough.

[AyushMukkanwar]

Please remove the links to private files in the change set comments, like cci:2://file:///home/ayush_mukkanwar/Dev/OSS/opentelemetry-cpp/sdk/test/trace/tracer_config_test.cc:76:0-78:2

No need to link to a file name and line number, just TracerConfig is enough.

sorry about that, just signed the cla.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.05%. Comparing base (61e550e) to head (f8e1d91).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3942      +/-   ##
==========================================
- Coverage   90.06%   90.05%   -0.01%     
==========================================
  Files         226      226              
  Lines        7229     7229              
==========================================
- Hits         6510     6509       -1     
- Misses        719      720       +1     

Files with missing lines	Coverage Δ
sdk/include/opentelemetry/sdk/logs/logger_config.h	100.00% <100.00%> (ø)
...k/include/opentelemetry/sdk/metrics/meter_config.h	100.00% <100.00%> (ø)
...dk/include/opentelemetry/sdk/trace/tracer_config.h	100.00% <100.00%> (ø)
sdk/src/logs/logger_config.cc	100.00% <100.00%> (ø)
sdk/src/metrics/meter_config.cc	100.00% <100.00%> (ø)
sdk/src/trace/tracer_config.cc	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[marcalff]

Looks good overall.

Please add a CHANGELOG entry, and a new entry in the important notes section:

In TracerConfig(bool) and friends, the meaning of the bool parameter has changed, user code needs to be adjusted.

(to reword of course)

[marcalff]

CI break is:

CHANGELOG.md:86:81 MD013/line-length Line length [Expected: 80; Actual: 139]
CHANGELOG.md:87:81 MD013/line-length Line length [Expected: 80; Actual: 96]

[marcalff]

LGTM, thanks for the fix.

Will merge after formatting fixes in CHANGELOG.md