Select local instance ID automatically
If the user creates an instance with --local-instance without the ID,
acloud selects an unused instance directory. Each directory is guarded
by a lock file, so the testing infrastructure can run multiple acloud
processes in parallel.
This commits also removes IsLocalImageOccupied to simplify the logic.
Test: acloud-py3-dev create --local-instance --local-image
Test: acloud-py3-dev delete --local-only
Bug: 160942364
Bug: 149602560
Change-Id: Ic095883c98261b2419d88618991b333bed6dcb67
10 files changed