chore: Remove unused functionality and imports ValidationHelper.cs (#818)

Author: Joseph2910

application/CohortManager/src/Functions/Shared/Common/ValidationHelper.cs

@@ -1,13 +1,11 @@
 namespace Common;
 
-using System.Diagnostics.Eventing.Reader;
 using System.Globalization;
-using System.Reflection.Metadata;
 
 public static class ValidationHelper
 {
 
-    private static readonly string[] DateFormats = ["yyyyMMdd", "yyyyMM", "yyyy", "yyyy-MM-dd", "dd/MM/yyyy HH:mm:ss", "d/MM/yyyy hh:mm:ss tt", "dd/MM/yyyy HH:mm:ss tt", "yyyy"];
+    private static readonly string[] DateFormats = ["yyyyMMdd", "yyyyMM", "yyyy", "yyyy-MM-dd", "dd/MM/yyyy HH:mm:ss", "d/MM/yyyy hh:mm:ss tt", "dd/MM/yyyy HH:mm:ss tt"];
     private static readonly string NilReturnFileNhsNumber = "0000000000";
     // Validates that the date is not in the future and that it is in one of the expected formats
     public static bool ValidatePastDate(string dateString)
@@ -19,11 +17,7 @@ public static bool ValidatePastDate(string dateString)
         }
         return false;
     }
-    public static bool IsValidDate(string dateString)
-    {
-        var date = ParseDate(dateString);
-        return date.HasValue;
-    }
+
     public static bool ValidateNHSNumber(string nhsNumber)
     {
         // Check the NHS number is a number