[backend/database] Remove redundant index on the marker table

This index is identical to the composite primary key, and therefore redundant.

Iceshrimp.Backend/Core/Database/Migrations/DatabaseContextModelSnapshot.cs

@@ -1638,9 +1638,6 @@ namespace Iceshrimp.Backend.Core.Database.Migrations
 
                     b.HasIndex("UserId");
 
-                    b.HasIndex("UserId", "Type")
-                        .IsUnique();
-
                     b.ToTable("marker");
                 });
 

Iceshrimp.Backend/Core/Database/Migrations/v2024.1-beta1/20240419181840_RemoveRedundantMarkerIndex.cs

@@ -0,0 +1,31 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+
+#nullable disable
+
+namespace Iceshrimp.Backend.Core.Database.Migrations
+{
+    /// <inheritdoc />
+    [DbContext(typeof(DatabaseContext))]
+    [Migration("20240419181840_RemoveRedundantMarkerIndex")]
+    public partial class RemoveRedundantMarkerIndex : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_marker_userId_type",
+                table: "marker");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_marker_userId_type",
+                table: "marker",
+                columns: new[] { "userId", "type" },
+                unique: true);
+        }
+    }
+}

Iceshrimp.Backend/Core/Database/Tables/Marker.cs

@@ -7,7 +7,6 @@ namespace Iceshrimp.Backend.Core.Database.Tables;
 
 [Table("marker")]
 [Index(nameof(UserId))]
-[Index(nameof(UserId), nameof(Type), IsUnique = true)]
 [PrimaryKey(nameof(UserId), nameof(Type))]
 public class Marker
 {