bionic libc test: clean up tests for getgrouplist

Since the tests for getgrouplist will be implemented in bionic/tests
directory, the test files and setting will be deleted from here.

Change-Id: Ib5ece65ef2475ae8acc9ce5bfd2a255b734aa906
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
2 files changed