Ensure that android.test tests pass

It looks as though the tests in test-runner/tests have not actually been
run successfully for over 7 years. As a result they have degraded. This
change fixes the tests so that they will pass and provides instructions
on how to run them.

TestCaseUtilTest.testGetTestCaseNamesForTestSuiteWithSuiteMethod
    This fails because it expected 2 names to be returned but only
    returns 0. The reason for that is although TwoTestsInTestSuite has a
    Test suite() method that does create a TestSuite with two tests the
    TestCaseUtil method does not actually call suite(). Instead, because
    TwoTestsInTestSuite is a TestSuite it just calls the tests() method
    on it which returns an empty Enumeration because TwoTestsInTestSuite
    is empty.

    The support for "static Test suite() {}" is broken but fixing this
    will affect the behavior of InstrumentationTestRunner which is used
    in thousands of different places both in and outside Google and so
    could cause untold problems.

TestSuiteBuilderTest.testIncludeAllPackagesUnderHere
    Reformat the list, one per line and then add missing name
    "testPublicConstructor".

ErrorTest/FailingTest
    These tests are not meant to be run on their own, only as part of a
    separate test. The RunAsPartOfSeparateTest annotation was added to
    allow these to be excluded using notAnnotation as shown in the
    instructions for running the tests.

Bug: 30188076
Test: followed new instructions in test-runner/tests/Android.mk
Change-Id: I60e7bee9cd08a9ab7777a2578fc58da772de5c1f