Removed unused variable

Author: fabioromano1

src/java.base/share/classes/java/math/BigDecimal.java

@@ -2168,7 +2168,6 @@ public BigDecimal sqrt(MathContext mc) {
             // for special cases that could run faster.
 
             int preferredScale = this.scale/2;
-            BigDecimal zeroWithFinalPreferredScale = valueOf(0L, preferredScale);
 
             BigDecimal result;
             if (mc.roundingMode == RoundingMode.UNNECESSARY || mc.precision == 0) { // Exact result requested