refactor: 修复测试用例没有traceprovider的问题 --story=126421543

# Reviewed, transaction id: 53415

Author: dengyh

gcloud/core/trace.py

@@ -16,6 +16,7 @@
 from functools import wraps
 
 from opentelemetry import trace
+from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import SpanProcessor
 from opentelemetry.trace import SpanKind
 
@@ -54,9 +55,14 @@ def propagate_attributes(attributes: dict):
 
     provider = trace.get_tracer_provider()
 
+    if not provider:
+        provider = TracerProvider()
+
     # Add a span processor that sets attributes on every new span
     provider.add_span_processor(AttributeInjectionSpanProcessor(attributes))
 
+    trace.set_tracer_provider(provider)
+
 
 @contextmanager
 def start_trace(span_name: str, propagate: bool = False, **attributes):