[ATest] Create ATest's own local minimum config.

1. Move common configuration to local_min_base.xml
2. Keep original logsaver FileSystemLogSaver declaration in
local_min.xml
3. Declare ATest’s own logsaver in atest_local_min.xml

Bug:124819561

Test: source && lunch
     tools/tradefederation/core/tests/run_tradefed_tests.sh --class com.android.tradefed.result.ATestFileSystemLogSaverTest

Change-Id: Ia909e92e763b90ec95b1f415aac2ea769c25306a
3 files changed