Switch assistant to HEAVY_CLICK effect on devices without haptic composition.

EFFECT_DOUBLE_CLICK is used for REJECT situations so it
feels like a mistake. EFFECT_HEAVY_CLICK was used for
EDGE_SQUEEZE previously so it's a better choice anyway.

Bug: 182381083
Fixes: 186767913
Test: long-press power
Change-Id: Iea474367a3f09a842b644cff7e2e2f05d6ddac49