feat(config): wire top-level log_level field in declarative configuration

[ocelotl]

Description

The declarative configuration schema has a top-level log_level field that controls the SDK's internal diagnostic logging verbosity. It was parsed and validated by the schema loader but never read by configure_sdk — so setting it in a config file had no observable effect.

This PR wires log_level into configure_sdk: when the field is present, it maps the OTel SeverityNumber value to a Python logging level and sets it on the opentelemetry root logger. All numbered severity variants (e.g. debug2, warn3) collapse to the same Python tier.

Mapping:

OTel severity	Python level
trace, trace2–4	DEBUG
debug, debug2–4	DEBUG
info, info2–4	INFO
warn, warn2–4	WARNING
error, error2–4	ERROR
fatal, fatal2–4	CRITICAL

When log_level is absent the logger is untouched, preserving existing behaviour.

Fixes the gap noted in #5347 (log_level ❌ — No tracker yet).

Type of change

• Bug fix / gap closure (non-breaking change that makes existing behaviour match the spec)

How Has This Been Tested?

Three new unit tests in test_sdk.py:

• test_sets_opentelemetry_logger_level — verifies a specific severity sets the expected level
• test_absent_log_level_leaves_logger_unchanged — verifies no mutation when field is absent
• test_severity_number_variants_map_correctly — exhaustive subTest over all tiers (trace, debug, info, warn, error, fatal + their *4 variants)

Does This PR Require a Contrib Repo Change?

• Yes.
• No.

Checklist

• Followed the style guidelines of this project
• Changelogs have been updated (will add once PR number is known)
• Unit tests have been added
• Documentation has been updated (spec-conformance.md row will change from ❌ to ✅)

🤖 Generated with Claude Code

[linux-foundation-easycla]

• ✅ login: ocelotl / name: Diego Hurtado (31e401c, 7c3cb3a)
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