Changed test to accompany new user

Author: Oyvind Timian Dokk Husveg

exercise.tests/IntegrationTests/CohortTests.cs

@@ -269,7 +269,7 @@ public async Task CreateCohort(string email, string password, string cohortName,
         [TestCase(TeacherEmail, TeacherPassword, 350, 1, 1, "User with Id 350 not found.", HttpStatusCode.BadRequest)]
         [TestCase(TeacherEmail, TeacherPassword, 1, 20, 1, "Cohort with Id 20 not found.", HttpStatusCode.BadRequest)]
         [TestCase(TeacherEmail, TeacherPassword, 1, 1, 10, "The specified course is not part of this cohort.", HttpStatusCode.BadRequest)]
-        [TestCase(TeacherEmail, TeacherPassword, 11, 1, 1, "User is already in the specified course in the cohort.", HttpStatusCode.BadRequest)]
+        [TestCase(TeacherEmail, TeacherPassword, TeacherId, 3, 3, "User is already in the specified course in the cohort.", HttpStatusCode.BadRequest)]
         [TestCase(StudentEmail1, StudentPassword1, 1, 3, 1, "You are not authorized to add a user to a cohort.", HttpStatusCode.Forbidden)]
         public async Task AddUserToCohortAndDeleteUser(
             string email,