revert: correlate business spans with active observability trace (#465)

Reverts #465 (src/agentex/lib/core/tracing/obs_ids.py and trace.py). The dependent open PRs #466/#467/#471 build on obs_ids and are intentionally left open for now.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: NiteshDhanpal

src/agentex/lib/core/tracing/obs_ids.py

@@ -11,7 +11,6 @@
 from agentex.types.span import Span
 from agentex.lib.utils.logging import make_logger
 from agentex.lib.utils.model_utils import recursive_model_dump
-from agentex.lib.core.tracing.obs_ids import obs_correlation
 from agentex.lib.core.tracing.span_error import set_span_error
 from agentex.lib.core.tracing.span_queue import (
     SpanEventType,
@@ -80,12 +79,6 @@ def start_span(
 
         serialized_input = recursive_model_dump(input) if input else None
         serialized_data = recursive_model_dump(data) if data else None
-        # Tag the business span with the active observability trace_id/span_id
-        # (OTel/ddtrace) so it can be correlated to the per-turn obs trace. The
-        # business trace_id stays the run-level task id -- see obs_ids.py.
-        obs = obs_correlation()
-        if obs:
-            serialized_data = {**(serialized_data or {}), **obs}
         id = str(uuid.uuid4())
 
         span = Span(
@@ -236,12 +229,6 @@ async def start_span(
 
         serialized_input = recursive_model_dump(input) if input else None
         serialized_data = recursive_model_dump(data) if data else None
-        # Tag the business span with the active observability trace_id/span_id
-        # (OTel/ddtrace) so it can be correlated to the per-turn obs trace. The
-        # business trace_id stays the run-level task id -- see obs_ids.py.
-        obs = obs_correlation()
-        if obs:
-            serialized_data = {**(serialized_data or {}), **obs}
         id = str(uuid.uuid4())
 
         span = Span(