Halve WPT processes to avoid flaky webserver issues.
Halve WPT processes to avoid flaky webserver issues.

ALikhachev/saltfs,UK992/saltfs,servo/saltfs,UK992/saltfs,UK992/saltfs,setupminimal/saltfs,setupminimal/saltfs,rwaweber/saltfs,rwaweber/saltfs,servo/saltfs,setupminimal/saltfs,ALikhachev/saltfs,ALikhachev/saltfs,rwaweber/saltfs