Previously, we needed to manually specify a ChromeDriver version to
download on CI that would be compatible with the browser version
provided by the docker image used to run the tests. This was kept in the
`CI_CHROMEDRIVER_VERSION_ARG` environment variable.

With recent commits, we use the browser provided by `puppeteer` and can
determine the correct ChromeDriver version programmatically. Therefore,
we no longer need the `CI_CHROMEDRIVER_VERSION_ARG` environment
variable.

NOTE:
There is still one place (the `bazel-schematics` integration project)
where a hard-coded ChromeDriver version is necessary. Since I am not
sure what is the best way to refactor the tests to not rely on a
hard-coded version, I left it as a TODO for a follow-up PR.

PR Close #35381