Ensure OTel SDK backward compatibility with older API versions

[wangzlei]

Describe your environment

OS: (e.g, Ubuntu) Any
Python version: (e.g., Python 3.9.10) Any
SDK version: (e.g., 1.25.0) 1.40.0
API version: (e.g., 1.25.0) Any version lower than 1.40.0, for example 1.33.1

What happened?

PR #4867 introduced hard imports of symbols only available in API 1.40.0+.
This breaks zero-code instrumentation when:

• User application pins opentelemetry-api to an older version lower than 1.40.0
• SDK(1.40.0) + instrumentation(0.61) packages are injected at runtime via PYTHONPATH

Steps to Reproduce

# 1. Simulate user application with older API
pip install opentelemetry-api==1.39.0

# 2. Inject SDK 1.40.0 via PYTHONPATH (simulating runtime injection)
pip install --target /opt/otel opentelemetry-sdk==1.40.0
export PYTHONPATH="/opt/otel:$PYTHONPATH"

# 3. Launch with zero-code instrumentation
opentelemetry-instrument python myapp.py
# → ImportError: cannot import name '...' from 'opentelemetry.api...'

Expected Result

Use defensive imports (try/except) for symbols introduced in newer API versions, and fall back gracefully.

Actual Result

ImportError on startup. Zero-code instrumentation completely fails with no actionable guidance.

Additional context

No response

Would you like to implement a fix?

None

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