tools: fetch googletest dependency for V8 CI

gtest_prod.h is not enough to build V8's cctests.

PR-URL: https://github.com/nodejs/node/pull/38990


Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>