Enable multidex for CtsAppTestCases

This target is already close to the single dex limit, even with
instrumentation disabled. Enable multi-dex to fix builds with
transient and organize size growth.

Bug: 233974690
Test: m CtsAppTestCases + presubmit
Merged-In: I6e7d6bcc9a3c310141fe8df6972472d5b412b4ee
Change-Id: I6e7d6bcc9a3c310141fe8df6972472d5b412b4ee
(cherry picked from commit d40e10d96981dca47d25cd132627804767670b80)