[BrightnessToast]: fix string being ellisped in wrong place

Remove the line breaking charactor in the middle of the string to avoid
the sting being ellipsed in wrong place when chaning the font scale
bigger (e.g. font_size  > 1.1 - 1.2)

Fix: 397267724
Fix: 396747791
Flag: EXEMPT string resources update

Test: manual
Change-Id: I3eb19db0366a378bbea0f44db3d5e3f02de744e0