Fix lacros_chrome_browsertests not on ci/cq

lacros_chrome_browsertests, lacros_chrome_browsertests_run_in_series
are currently not on ci/cq.
This regression was introduced in crrev.com/c/3069191
when I'm adding the version skew version of these tests.
This seems like a bug in json generator because adding a
variant of a test suite will delete the non-variant of the
test suite. And it's a bit hard to find out during review
because chromiumos.json file only contains added lines.

Bug: 1249291
Change-Id: Ie3674c9b22fbb0314e7894a6240518d02c48dad2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3166554


Commit-Queue: Sven Zheng <svenzheng@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@google.com>
Cr-Commit-Position: refs/heads/main@{#922633}