C#: Update expected test output.

Author: michaelnebel

csharp/ql/test/query-tests/Language Abuse/MissedReadonlyOpportunity/MissedReadonlyOpportunity.expected

@@ -1,8 +1,4 @@
-#select
 | MissedReadonlyOpportunity.cs:3:16:3:19 | Bad1 | Field 'Bad1' can be 'readonly'. |
 | MissedReadonlyOpportunity.cs:4:14:4:17 | Bad2 | Field 'Bad2' can be 'readonly'. |
-| MissedReadonlyOpportunity.cs:45:19:45:24 | Parent | Field 'Parent' can be 'readonly'. |
 | MissedReadonlyOpportunity.cs:46:19:46:22 | Left | Field 'Left' can be 'readonly'. |
 | MissedReadonlyOpportunityBad.cs:3:9:3:13 | Field | Field 'Field' can be 'readonly'. |
-testFailures
-| MissedReadonlyOpportunity.cs:45:19:45:24 | Field 'Parent' can be 'readonly'. | Unexpected result: Alert |