Switch app bubble overflow removals to a dismiss / cancel

Treating a removal like a cancel is essentially the same as what
was being done before & minimizes the number of paths that are
used here.

Test: atest BubblesTest#testShowOrHideAppBubble_addsFromOverflow
Bug: 334175587
Change-Id: Ic664739b02857893cd37bfcdc6cf1050cbec8132