Respect ART_APEX_DATA for default artifact dir

This change does not change the default artifact directory. It just
makes odrefresh not define the default directory by itself, but relies
on GetArtApexData from libartbase instead (which has the same default).

Bug: 206468124
Test: Run odrefresh in the VM. No longer seeing files in the
      hard-coded directory.
Test: atest art_standalone_odrefresh_tests
Test: atest art_standalone_libartbase_tests
Change-Id: I45bcc145dbccb3b953f359f6c10fa186f251600c
9 files changed