NIU Tooltip : tooltip overlap issue fix

Overlay is getting updated multiple times, So If a tooltip is getting
shown then next overlay update call will trigger new tooltip regardless of current tooltip behavior.

If a tooltip is getting shown then other tooltips should not be triggered. Added a check for this.

Bug: 194458724
Test: Local build and run on Pixel 4a
Change-Id: I5266ddd7cfa84258b46dc14846d77872752ac442
(cherry picked from commit ced47f4ae652987f746daeec2367d184b1d63937)