Split query (#1449)

Closes
https://github.com/SoftUni-Internal/exam-systems-issues/issues/your_issue_number

**Summary of the changes made**:
1. {Describe your changes in the list}
2.

Author: gogo4ds

Services/UI/OJS.Services.Ui.Data/Implementations/ParticipantsDataService.cs

@@ -13,10 +13,10 @@ namespace OJS.Services.Ui.Data.Implementations
 
     public class ParticipantsDataService : DataService<Participant>, IParticipantsDataService
     {
+        private readonly OjsDbContext db;
+
         public ParticipantsDataService(OjsDbContext db)
-            : base(db)
-        {
-        }
+            : base(db) => this.db = db;
 
         public Task<Participant?> GetByContestByUserAndByIsOfficial(
             int contestId,
@@ -26,19 +26,31 @@ public ParticipantsDataService(OjsDbContext db)
                 .GetAllByContestByUserAndIsOfficial(contestId, userId, isOfficial)
                 .FirstOrDefaultAsync();
 
-        public Task<Participant?> GetWithContestAndSubmissionDetailsByContestByUserAndIsOfficial(int contestId, string userId, bool isOfficial)
-            => this.GetAllByContestByUserAndIsOfficial(contestId, userId, isOfficial)
+        public async Task<Participant?> GetWithContestAndSubmissionDetailsByContestByUserAndIsOfficial(int contestId, string userId, bool isOfficial)
+        {
+            var participant = await this.GetAllByContestByUserAndIsOfficial(contestId, userId, isOfficial)
                 .Include(p => p.User)
-                .Include(p => p.Contest)
-                    .ThenInclude(c => c.Category)
-                .Include(p => p.Contest)
-                        .ThenInclude(c => c.ProblemGroups)
-                            .ThenInclude(pg => pg.Problems)
-                                .ThenInclude(p => p.SubmissionTypesInProblems)
-                                    .ThenInclude(sp => sp.SubmissionType)
                 .Include(p => p.ProblemsForParticipants)
                 .FirstOrDefaultAsync();
 
+            var contest = await this.db.Contests.Where(c => contestId == c.Id)
+                .Include(c => c.Category)
+                .Include(c => c.ProblemGroups)
+                    .ThenInclude(pg => pg.Problems)
+                    .ThenInclude(p => p.SubmissionTypesInProblems)
+                    .ThenInclude(sp => sp.SubmissionType)
+                .FirstOrDefaultAsync();
+
+            if (participant == null || contest == null)
+            {
+                return null;
+            }
+
+            participant.ContestId = contestId;
+            participant.Contest = contest;
+            return participant;
+        }
+
         public IQueryable<Participant> GetWithProblemsForParticipantsByContestAndUser(int contestId,
             string userId)
             => this.GetAllByContestAndUser(contestId, userId)