[OBO] OBO Logging & Correlation

[anushakolan]

Add required observability for OBO without logging PII.

1. Log:

   1. OBO success/failure
   2. token cache hit/miss
   3. user identifier (oid OR sub)
   4. tenant ID

2. Propagate OpenTelemetry correlation ID

3. Set correlation values in SQL SESSION_CONTEXT when enabled

4. Ensure SESSION_CONTEXT is not used for authorization