fix(configuration): add missing config fallback defaults for file/env consistency

[MikeGoldsmith]

Which problem is this PR solving?

Several spec-defined default values were missing or inconsistent between FileConfigFactory (YAML config) and EnvironmentConfigFactory (env vars), causing different behavior depending on config source.

Key issues:

• BLRP schedule_delay defaulted to 5000ms (BSP value) instead of the spec-defined 1000ms for batch log record processors
• log_level defaulted to 'info' in file config but was unset in env config
• Tracer provider limits (event_count_limit, link_count_limit, etc.) were initialized in env config but not applied as defaults in file config
• Meter provider exemplar_filter defaulted to 'trace_based' in env config but not in file config

Short description of the changes

FileConfigFactory.ts:

• Split applyBatchProcessorDefaults into separate span (5000ms) and log (1000ms) schedule_delay defaults
• Add tracer provider limits defaults: event_count_limit, link_count_limit, event_attribute_count_limit, link_attribute_count_limit (all 128)
• Add logger provider attribute_count_limit default (128)
• Add meter provider exemplar_filter default ('trace_based')

utils.ts:

• Add log_level: 'info' to initializeDefaultConfiguration() so env-based config matches file-based config

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

82 configuration package tests pass. 189 sdk-node tests pass. Full repo compiles cleanly.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

Closes #5945

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.87%. Comparing base (81e20d0) to head (69c2fb2).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6717   +/-   ##
=======================================
  Coverage   94.86%   94.87%           
=======================================
  Files         376      376           
  Lines       12712    12732   +20     
  Branches     2883     2896   +13     
=======================================
+ Hits        12059    12079   +20     
  Misses        653      653           

Files with missing lines	Coverage Δ
...al/packages/configuration/src/FileConfigFactory.ts	98.87% <100.00%> (+0.14%)	⬆️
experimental/packages/configuration/src/utils.ts	98.03% <ø> (ø)

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[trentm]

I would like to hold on these changes. See the discussion at #6679 (comment) about where defaults should be applied for declarative config handling.

tl;dr: I don't think the "parse" handling in the configuration package should be adding any defaults to the parsed config object.

I'm not going to block, though. While I hope the #6679 discussion is resolved soon enough, it has been stalled for a little while.

[MikeGoldsmith]

Moving to draft until #6679 is resolved

[MikeGoldsmith]

Closing in favour of #6788, which applies the salvageable fixes (BLRP schedule_delay = 1000 default in sdk-node, log_level default in env factory init) at the consumer boundary instead of the parse step. The other defaults from this PR turned out to be either automatic once #6765 lands (the SDK applies its own defaults), redundant with existing sdk-node code (limits), or unused (exemplar_filter isn't consumed yet).