Enable 'use_swarming_recipe_to_trigger' for builder 'chromeos-amd64-generic-rel'

Now that 1131821 is fixed, we should no longer see failures as mentioned in https://crrev.com/c/2425924

Bug: 894045
Change-Id: I9ea229a6d9be975b27cde94f362d42016e68f6b2
Led-Recipes-Tester-Builder: luci.chromium.try:chromeos-amd64-generic-rel
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/build/+/2434413
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Junji Watanabe <jwata@google.com>
Commit-Queue: Ye Kuang <yekuang@google.com>
diff --git a/recipes/recipe_modules/chromium_tests/builders/chromium_chromiumos.py b/recipes/recipe_modules/chromium_tests/builders/chromium_chromiumos.py
index 2aa3e95..c2ada3c 100644
--- a/recipes/recipe_modules/chromium_tests/builders/chromium_chromiumos.py
+++ b/recipes/recipe_modules/chromium_tests/builders/chromium_chromiumos.py
@@ -114,6 +114,7 @@
         cros_board='amd64-generic'),
     _config(
         'chromeos-amd64-generic-rel',
+        chromium_tests_apply_config=['use_swarming_recipe_to_trigger'],
         cros_board='amd64-generic',
         checkout_qemu_image=True,
         isolate_server='https://isolateserver.appspot.com'),