default_timeout: Migrate to api.time.timeout()

Migrate from api.context(deadline=...) to api.time.timeout(...).

Change-Id: Iccc1ee9a141790189714de80de88e20c90f85d42
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/151971
Reviewed-by: Anthony Fandrianto <atyfto@google.com>
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/recipe_modules/default_timeout/api.py b/recipe_modules/default_timeout/api.py
index 662612e..18c550c 100644
--- a/recipe_modules/default_timeout/api.py
+++ b/recipe_modules/default_timeout/api.py
@@ -17,7 +17,6 @@
 import dataclasses
 
 from recipe_engine import recipe_api
-from PB.go.chromium.org.luci.lucictx import sections as sections_pb2
 from RECIPE_MODULES.fuchsia.utils import nice_duration
 
 
@@ -53,12 +52,8 @@
         with self.m.step.nest(f'timeout {nice_duration(timeout_sec)}'):
             pass
 
-        deadline = sections_pb2.Deadline()
-        deadline.soft_deadline = current_time_sec + timeout_sec
-        deadline.grace_period = 30.0
-
         try:
-            with self.m.context(deadline=deadline):
+            with self.m.time.timeout(timeout_sec):
                 yield
 
         finally: