Move RFHM browser tests to the embedded test server.

Using the spawned test server leads to flaky tests on Android, as test
server startup in a separate process takes up quite a bit of time. This
CL moves most tests away from this setup to use the embedded test server,
which runs in-process and doesn't have such a startup cost.

BUG=357747, 418236

Review URL: https://codereview.chromium.org/1378403002

Cr-Commit-Position: refs/heads/master@{#351910}
2 files changed