Update ub-uiautomator to 2.1.5

The ub-uiautomator 2.1.5
 - fixes UiObject2.click() bugs for multidisplay support.
 - adds UiObject2.click(Point) for clicking on arbitrary point.

Bug: 163106316
Bug: 182240558
Test: None
(cherry-pick commit 182e2d93d81d1acc8f53e7ffb3a5a717a0d49f80 from aosp/android11-tests-dev)

Change-Id: Icb71df2c6afcd2bea44e088d825f7f84ed13f9e7
2 files changed