testing: Allow adb sync to succeed when vendor is full

Only sync /data and /system. Otherwise we cannot run any target tests because
syncing fails with this error message:

adb: error: failed to copy
'/ssd3/yamauchi/android/repos/aosp-master7/out/target/product/angler/vendor/lib64/libril.so'
to '/vendor/lib64/libril.so': remote write failed: No space left on
device

Bug: 38246208
Change-Id: I33ab58f3577836cb867a7f705c02a48b7ac6f60b