C#: Update test expected output.

Author: michaelnebel

csharp/ql/test/library-tests/properties/Properties19.expected

@@ -8,4 +8,5 @@
 | properties.cs:146:24:146:27 | Prop | properties.cs:160:21:160:26 | access to property Prop | properties.cs:148:13:148:15 | get_Prop |
 | properties.cs:166:28:166:32 | Value | properties.cs:192:13:192:20 | access to property Value | properties.cs:169:13:169:15 | set_Value |
 | properties.cs:166:28:166:32 | Value | properties.cs:193:25:193:32 | access to property Value | properties.cs:168:13:168:15 | get_Value |
+| properties.cs:175:29:175:33 | Value | properties.cs:188:13:188:20 | access to property Value | properties.cs:169:13:169:15 | set_Value |
 | properties.cs:175:29:175:33 | Value | properties.cs:189:25:189:32 | access to property Value | properties.cs:177:13:177:15 | get_Value |