Remove unused using

src/Features/Core/Portable/EncapsulateField/AbstractEncapsulateFieldService.cs

@@ -13,7 +13,6 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeGeneration;
 using Microsoft.CodeAnalysis.Editing;
-using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.Formatting;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.PooledObjects;