Use isolated: true instead of test_per_src: true in libnativebridge_tests

libnativebridge_tests uses test_per_src: true to avoid running
multiple tests in the same process.  gtest_isolated uses separate
processes for each test, but without the various incompatibilities
caused by test_per_src.  Switch to isolated: true instead.

Create a temporary directory in the constructor of the shared
NativeBridgeTest base class instead and put the code_cache directory
inside it to keep the tests from trying to modify the current
directory.

Also add the tests to TEST_MAPPING and remove the preupload check.

Bug: 189484095
Test: atest --host libnativebridge_tests
Test: atest libnativebridge_tests
Flag: TEST_ONLY
Change-Id: Iea522c1895f1f5996b10e545c44d6b00bda1ee3d
20 files changed