Set base_dir of microdroid to system am: a313e56e87

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/1589311

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Idb982181de7b4081c2bebb04187ccd092f70da23
tree: 401390d59953a046bdf4516421d267e326966308
  1. apex/
  2. authfs/
  3. docs/
  4. microdroid/
  5. tests/
  6. virtmanager/
  7. .clang-format
  8. PREUPLOAD.cfg