Add .presubmit to .bazelignore

Change-Id: Iafad412eaf0dc7e21c9ac14f5d59a733624319ea
diff --git a/.bazelignore b/.bazelignore
index ddee9cb..9615219 100644
--- a/.bazelignore
+++ b/.bazelignore
@@ -1 +1,2 @@
 .cipd
+.presubmit