Speeding up testDragShortcutToMultipleWorkspaceCells in presubmit

On foldable, presubmit P90 is 38 min, and the requirement is to fit in
30 min.

testDragShortcutToMultipleWorkspaceCells takes around 3 min.
Making it enumerate less combinations in presubmit.

Bug: 295939967
Test: presubmit
Flag: N/A
Change-Id: Ic47223b3800fe502ed152488a2940f41c0edfb88