If a test fails without unregistering an agent, other tests will see their requests match the old agent. That means any test failing will fail all subsequent tests, which is not very helpful. Solve this by making sure the agents are unregistered before the test ends. Also ensure the requests are unregistered. Test: NetworkAgentTest Change-Id: I2c167803d478d31fd85dc6e6e621f35d36c68fb4