kokoro/apt_repo.sh: Stop automatic updates

Automatic updates should not run during this build.

BUG=none
TEST=kokoro

Change-Id: I055e04acf74d9f31d712f60a83f27a1da97970db
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/containers/cros-container-guest-tools/+/3593417
Reviewed-by: David Munro <davidmunro@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: James Ye <jamesye@google.com>
diff --git a/kokoro/apt_repo.sh b/kokoro/apt_repo.sh
index 0cb7e10..5ec252c 100755
--- a/kokoro/apt_repo.sh
+++ b/kokoro/apt_repo.sh
@@ -9,6 +9,7 @@
 
 main() {
     require_kokoro_artifacts
+    stop_apt_daily
 
     sudo apt-get -q update
     sudo apt-get -q -y install reprepro