types: unconditionally divide by 2 because of integer truncation ⌊x/2⌋ (#8202)

Simplify the code in Dec.Power to unconditionally divide by 2, since:
    x /= 2
is the same result for both even and odd integers, and produces the
floor of the result of x/2 -> ⌊x/2⌋:
    99/2 ~> 49.5 ⌊49.5⌋ = 49
    98/2 ~> 49.0 ⌊49.0⌋ = 49
aka "integer truncation".

Fixes #7924

types/decimal.go

@@ -394,12 +394,10 @@ func (d Dec) Power(power uint64) Dec {
 	tmp := OneDec()
 
 	for i := power; i > 1; {
-		if i%2 == 0 {
-			i /= 2
-		} else {
+		if i%2 != 0 {
 			tmp = tmp.Mul(d)
-			i = (i - 1) / 2
 		}
+		i /= 2
 		d = d.Mul(d)
 	}