libsnapshot: Disable 32-bit VTS tests on 64-bit systems.

These tests don't work because 32-bit dependencies are not normally
packaged on a 64-bit system.

Bug: 263062262
Test: builds
Change-Id: I68859a9e9c029a528ee12c02569a3693261c7251
(cherry picked from commit 32fa3e96)