[ci] Do not exit on success

Before, CI was exiting when an exit code of 0 was returned, failing
to build the installer script.

Tested with `bash -c 'source scripts/ci/build.sh; bazel_build output/ci'`
and checking output/ci for the installer.

--
MOS_MIGRATED_REVID=104647177
diff --git a/scripts/ci/build.sh b/scripts/ci/build.sh
index 2dd14e5..a73012e 100755
--- a/scripts/ci/build.sh
+++ b/scripts/ci/build.sh
@@ -157,7 +157,7 @@
   ${BUILD_SCRIPT_PATH} ${BAZEL_COMPILE_TARGET:-all} || retCode=$?
 
   # Exit for failure except for test failures (exit code 3).
-  if (( $retCode != 3 )); then
+  if (( $retCode != 0 && $retCode != 3 )); then
     exit $retCode
   fi