Use the test engine interface plain for some googlemock/googletest provided tests

The issues are as follows:
i. Some tests don't execute RUN_ALL_TESTS().
ii. Some tests incorrectly analyze the results when --gtest_list_tests is

specified on the command line.

iii. Some tests assume all tests are run (in order to analyze the results at

the end of the test program as part of Environment::TearDown()).

The above items cause Kyua googletest engine to bail, since there is spurious
output on the command line (in the case of i. and ii.), or failures/asserts are
needlessly triggered (in the case of iii.).

Add comments noting why the testcases cannot use the googletest interface, along
with their respective googletest issues.

Case ii: https://github.com/google/googletest/issues/2204
Case iii: https://github.com/google/googletest/issues/2205