Update bubble bar overflow to have a unique resId

This allows the overflow to be tested properly in end-to-end tests.

Flag: com.android.wm.shell.enable_bubble_bar
Test: atest OverflowBubbleTest (with other CL)
Bug: 347312208
Change-Id: Ice969434f9c40602c4b2d1a5baf6ba0509534a56
2 files changed