Fixing extracted public volume name.

The public volume created is read before its successfully mounted,
resulting in 'null' as volume name.
Adding a wait (2000ms) to allow volume being mounted.

Bug: 273077481
Test: atest AppCloningPublicVolumeTest
Change-Id: Ic0d43a789978cd72ffa3dc9521a41b0d0a4b4802
1 file changed