autoclick: Fix panel jumping issue when drag

Problem: Panel jumps down when drag starts.

Cause: LayoutParams.y is relative to the content area (below the status
bar), but when we calculate delta during drag, we use absolute screen Y
from getLocationOnScreen(), which includes the status bar height.

Fix: Subtract status bar height to avoid any "jump".

Video:
 - Before: http://shortn/_inTwbPw50q
 - After:  http://shortn/_znCNEgbKXU

Bug: b/413444209
Test: atest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: I809ca53168e070b1cfab0d57920cb9f859c74422