cbuildbot: Skip Update ChromeOSLKGM stage for basic-builder.

Do not update ChromeOS LKGM if on the basic-builder.

BUG=chromium:1096776
TEST=./run_pytest

Change-Id: I84e182ea662155ee9844f5e5fb5d7a3d82ed536b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2274299
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Commit-Queue: Navil Perez <navil@google.com>
Tested-by: Navil Perez <navil@google.com>
diff --git a/cbuildbot/builders/simple_builders.py b/cbuildbot/builders/simple_builders.py
index 8b16f58..23d42dd 100644
--- a/cbuildbot/builders/simple_builders.py
+++ b/cbuildbot/builders/simple_builders.py
@@ -533,7 +533,7 @@
         self._RunStage(report_stages.SlaveFailureSummaryStage)
 
       if config_lib.IsCanaryMaster(self._run):
-        if build_finished:
+        if build_finished and not self._run.config.basic_builder:
           self._RunStage(completion_stages.UpdateChromeosLKGMStage)
         else:
           logging.info(