Reduce unnecessary invocation of fillTaskInfo

The getTaskInfo invokes fillTaskInfo, which is heavy to fill lots of
fields. But the specified caller only needs 2 attributes of the task,
which is unnecessary to get entire task info that populates many
unrelated fields.

Bug: 297502610
Flag: EXEMPT remove unnecessary invocation
Test: atest DesktopModeLaunchParamsModifierTests
Change-Id: I99a9e5306bf16d614ab4f6791f399b3cfe4ff314