[Logging] Move error to warning for log context logs (#4758)

We're moving the logging level from error to warning for exceptions that
was caught during log context. We need to do this because this errors
are already handled in the uper level, but we want to log it as warning
to have visibility with the strucutred logs.

---------

Signed-off-by: Javan Lacerda <javanlacerda@google.com>

Author: javanlacerda

src/clusterfuzz/_internal/metrics/logs.py

@@ -795,7 +795,7 @@ def task_stage_context(stage: Stage):
       log_contexts.add_metadata('stage', stage)
       yield
     except Exception as e:
-      error(message='Error during task.')
+      warning(message='Error during task.')
       raise e
     finally:
       log_contexts.delete_metadata('stage')
@@ -816,7 +816,10 @@ def testcase_log_context(testcase: 'Testcase',
       log_contexts.add_metadata('fuzz_target', fuzz_target)
       yield
     except Exception as e:
-      error(message='Error during testcase context.')
+      # We've put as warning because this error will be
+      # handled in a upper level, and we would like to have
+      # a way to track it with the current context logs
+      warning(message='Error during testcase context.')
       raise e
     finally:
       log_contexts.delete_metadata('testcase')