test: Add cros-test-finder to test-services containers to build.

BUG=b:200620192
TEST=unittest, manual build_api call, led launch

Change-Id: I77176bc01ab826d6d231f6d7c5fb8e5b9adeda50
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3277122
Tested-by: Sean McAllister <smcallis@google.com>
Commit-Queue: Sean McAllister <smcallis@google.com>
Reviewed-by: Seewai Fu <seewaifu@google.com>
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
diff --git a/api/controller/test.py b/api/controller/test.py
index 0c75707..830eae0 100644
--- a/api/controller/test.py
+++ b/api/controller/test.py
@@ -166,6 +166,11 @@
             PLATFORM_DEV_DIR,
             'test/container/utils/build-dockerimage.sh'
         ),
+    'cros-test-finder':
+        os.path.join(
+            TEST_SERVICE_DIR,
+            'test_finder/docker/build-dockerimage.sh',
+        ),
 }