Add aliases for asserts in TestUtils

Most of the tests use public servers with the standard HTTP or HTTPS
port. This can be inferred by the assert method being called. Add
shortcut methods in TestUtils to use the default port. Keep the existing
methods public for cases where the standard port is not used (i.e.,
localhost).

Test: presubmit
Bug: none
Flag: EXEMPT test only
Change-Id: If2ee394b2f01de01c957d272b0260e3bdad742b2