Run chromedriver at WARNING so WebDriver command values are not logged

[akxue]

context

chromedriver ran with --log-level=INFO. at INFO it logs every WebDriver command and response with its values: sendKeys text, actions API keys, element property reads (including a password field's value), cookies, executeScript arguments and results, and full URLs. supervisord writes that to /var/log/supervisord/chromedriver, and the wrapper tails it to the VM console, so passwords typed by Selenium or other WebDriver clients ended up in VM logs.

changes

run chromedriver at --log-level=WARNING in the headful and headless images.

testing

• local repro with chromedriver 155 and chrome-headless-shell: at INFO, a sendKeys of a canary password shows up as COMMAND TypeElement { "text": ... }. at WARNING the log has no COMMAND or RESPONSE lines and no canary.
• nothing in the repo reads the chromedriver log file (grep).
• not tested: an image build.