[2/n] Re-enable tests that were disabled as part of desktop mode flag rollout

While rolling out the desktop mode flag, a number of tests were failing due to coexistence issues with desktop mode and the existing freeform and multi-display behaviours. As a result, these tests were temporarily
disabled on devices with desktop mode enabled.

However, following ag/27155182, a number of these tests are now passing
and can thus be re-enabled.

Fixes: 338196631
Test: atest CtsWindowManagerDeviceActivity:ActivityStarterTests
Change-Id: I637d33c1938b63f18476d9b63b082c6a7b1f1fa9