Write VNDK test logs to stdout

The logs are written to stderr by default and interleave the test
results that TradeFed parses. This commit configures the logger to write
to stdout.

Test: LD_LIBRARY_PATH=out/host/linux-x86/lib64 atest vts_vndk_files_test
Bug: 156715331
Change-Id: I5dd5754e6282bcf4b1fd748bb443c079dd668b35
3 files changed