Make SdkLoggerProvider.get() return noop Logger when no processors are configured

[thswlsqls]

Fixes #8836

Description

• SdkLoggerProvider.loggerBuilder() returns LoggerProvider.noop().loggerBuilder(name) when no LogRecordProcessor is configured, but get() skipped that check and always built a real SdkLogger.
• With no processors, get("x").isEnabled(Severity.INFO) returned true while loggerBuilder("x").build().isEnabled(...) returned false; the Logs SDK spec requires Enabled to return false when no processors are registered. The SdkLogger also allocated a record and counted otel.sdk.log.created on every emit before NoopLogRecordProcessor dropped it.
• Only direct SdkLoggerProvider.get() calls are affected; OpenTelemetrySdk.getLogsBridge().get() already routes through loggerBuilder().
• get() now returns LoggerProvider.noop().get(name) under the same isNoopLogRecordProcessor condition, matching loggerBuilder() and SdkMeterProvider. The check was lost in Optimize log hot path #4913, which replaced loggerBuilder(name).build() with a direct registry lookup.

Related: #8740 / #8815 (same shortcut for SdkTracerProvider), spec specification/logs/sdk.md "Enabled".

Testing done

• Added SdkLoggerProviderTest#get_NoProcessor_UsesNoop; it failed before the fix (SdkLogger vs DefaultLogger) and passes after.
• ./gradlew :sdk:logs:check — 90 tests + 22 testIncubating passed.
• ./gradlew :sdk:all:test — 23 tests passed.
• No public API change; docs/apidiffs unchanged.

[opentelemetry-pr-dashboard]

Pull request dashboard status

Waiting on maintainers · refreshed 2026-09-21 15:26 UTC

Merge when ready.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.37%. Comparing base (509182e) to head (3a8811f).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8838      +/-   ##
============================================
+ Coverage     91.34%   91.37%   +0.03%     
- Complexity    10652    10657       +5     
============================================
  Files          1010     1010              
  Lines         28696    28698       +2     
  Branches       3682     3682              
============================================
+ Hits          26212    26224      +12     
+ Misses         1683     1671      -12     
- Partials        801      803       +2     

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