Bug 1873986 - Fix dom/tests/mochitest/fetch/ when by blocking 3pc by default in TCP. r=bvandersloot,necko-reviewers,tschuster,kershaw

Depends on D217979

Differential Revision: https://phabricator.services.mozilla.com/D215353

build/pgo/server-locations.txt

@@ -105,9 +105,11 @@ https://example.com:443                privileged
 https://www.example.com:443            privileged
 https://test1.example.com:443          privileged
 https://test2.example.com:443          privileged
+https://test3.example.com:443
 https://example.org:443                privileged
 https://test1.example.org:443          privileged
 https://test2.example.org:443          privileged
+https://test3.example.org:443
 https://sub1.test1.example.org:443     privileged
 https://sub1.test2.example.org:443     privileged
 https://sub2.test1.example.org:443     privileged