Revert^2 "Prevent activity being launched on a display where canHostTasks()"

This reverts commit 395a6636.

Reason for revert: Reapply the change with test failure fixes

This fixes the test failures in ActivityStarterTests and
ActivityStarterTests by ensuring the Display object created in
TestDisplayContent class has canHostTasks is true by default.

Note that Display.canHostTasks should be false only for virtual displays
that should always be mirroring (i.e., MediaProjection is not null), or
for a display that can dynamically switch its content mode and has the
mirroring switch enabled. Since the mirroring switch is disabled by
default, the Display object created in TestDisplayContent should have
canHostTasks being true by default.

Bug: 424049071
Test: ActivityStarterTests
Test: RootWindowContainerTests
Change-Id: I8586f8f0b9840891388c811d3b4c574f7a9e2341