BUG #15076: Fix resetting of opacity range.

The code to reset the transfer function range as time changed didn't
reset the range for the scalar opacity function. Fixed that.

Change-Id: Ia3fada7e4e725f017cbb42629cb48b65ec6ae993
Merge topic '15076_fix_opacity_mapping_reset' into next

efe3ac35 BUG #15076: Fix resetting of opacity range.