Speed up dial timeout tests

[rosstimothy]

Leverage synctest to exercise client dial timeout tests instead of the tests sitting idle for the entire timeout. Tests were moved to api and now test against the api.Client directly instead of indirectly via the auth.Client to exercise tests against a fake dialer in the synctest bubble.

Comparison of the old and new test

$ time ./authclient.test -test.v -test.count=1  -test.run="TestClient_DialTimeout"
=== RUN   TestClient_DialTimeout
=== PAUSE TestClient_DialTimeout
=== CONT  TestClient_DialTimeout
=== RUN   TestClient_DialTimeout/dial_timeout_set_to_valid_value
=== PAUSE TestClient_DialTimeout/dial_timeout_set_to_valid_value
=== RUN   TestClient_DialTimeout/defaults_prevent_infinite_timeout
=== PAUSE TestClient_DialTimeout/defaults_prevent_infinite_timeout
=== CONT  TestClient_DialTimeout/defaults_prevent_infinite_timeout
=== CONT  TestClient_DialTimeout/dial_timeout_set_to_valid_value
--- PASS: TestClient_DialTimeout (0.00s)
    --- PASS: TestClient_DialTimeout/dial_timeout_set_to_valid_value (0.50s)
    --- PASS: TestClient_DialTimeout/defaults_prevent_infinite_timeout (20.00s)
PASS
________________________________________________________
Executed in   21.10 secs      fish           external
   usr time   82.91 millis    0.30 millis   82.61 millis
   sys time   44.29 millis    3.26 millis   41.02 millis


$ time ./api/client.test -test.v -test.count=1 -test.run="TestDialTimeout"
=== RUN   TestDialTimeout
=== PAUSE TestDialTimeout
=== CONT  TestDialTimeout
=== RUN   TestDialTimeout/dial_timeout_set_to_valid_value
=== RUN   TestDialTimeout/defaults_prevent_infinite_timeout
--- PASS: TestDialTimeout (0.00s)
    --- PASS: TestDialTimeout/dial_timeout_set_to_valid_value (0.00s)
    --- PASS: TestDialTimeout/defaults_prevent_infinite_timeout (0.00s)
PASS

________________________________________________________
Executed in    1.05 secs      fish           external
   usr time   27.57 millis    0.21 millis   27.36 millis
   sys time   12.28 millis    1.65 millis   10.63 millis

[backport-bot-workflows]

@rosstimothy See the table below for backport results.

Branch	Result
branch/v17	Failed
branch/v18	Failed