[coil] change "dummy" to "stub"

A few references are left behind: where we run an autotest that is
still called "dummy".

BUG=b:187793358
TEST=CQ passes

Change-Id: I98165c31088b0c7e9cfe170f2228e851a21975c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3526871
Tested-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Ram Chandrasekar <rchandrasekar@google.com>
Commit-Queue: Ram Chandrasekar <rchandrasekar@google.com>
diff --git a/scripts/build_api_unittest.py b/scripts/build_api_unittest.py
index de3979b..4e1b888 100644
--- a/scripts/build_api_unittest.py
+++ b/scripts/build_api_unittest.py
@@ -14,10 +14,10 @@
 def testSmoke(tmp_path, monkeypatch):
   """Basic sanity check"""
 
-  def dummy(*_args, **_kwargs):
+  def stub(*_args, **_kwargs):
     return True
 
-  monkeypatch.setattr(router_lib.Router, 'Route', dummy)
+  monkeypatch.setattr(router_lib.Router, 'Route', stub)
 
   input_json = tmp_path / 'input.json'
   output_json = tmp_path / 'output.json'