Remove defensive Dictionary copies

-NavigationExpandingExpressionVisitor: ToList() is not needed anymore, as we remove from IncludeTreeNode which inherites from Dictionary
- TableSharingConcurrencyTokenConvention: no need for deferring removal from collection and ToList() as entityTypeDictionary is Dictionary

Fixes #18598

Authored-by: Michał Czerwiński <mcr@spyro-soft.com>

src/EFCore.Relational/Metadata/Conventions/TableSharingConcurrencyTokenConvention.cs

@@ -234,31 +234,24 @@ public static bool IsConcurrencyTokenMissing(
 
         private static void RemoveDerivedEntityTypes<T>(Dictionary<IConventionEntityType, T> entityTypeDictionary)
         {
-            var toRemove = new HashSet<KeyValuePair<IConventionEntityType, T>>();
             var entityTypesWithDerivedTypes =
-                entityTypeDictionary.Where(e => e.Key.GetDirectlyDerivedTypes().Any()).ToList();
+                entityTypeDictionary.Where(e => e.Key.GetDirectlyDerivedTypes().Any());
             foreach (var entityType in entityTypeDictionary.Where(e => e.Key.BaseType != null))
             {
                 foreach (var otherEntityType in entityTypesWithDerivedTypes)
                 {
-                    if (toRemove.Contains(otherEntityType)
-                        || otherEntityType.Equals(entityType))
+                    if (otherEntityType.Equals(entityType))
                     {
                         continue;
                     }
 
                     if (otherEntityType.Key.IsAssignableFrom(entityType.Key))
                     {
-                        toRemove.Add(entityType);
+                        entityTypeDictionary.Remove(entityType.Key);
                         break;
                     }
                 }
             }
-
-            foreach (var entityType in toRemove)
-            {
-                entityTypeDictionary.Remove(entityType.Key);
-            }
         }
     }
 }

src/EFCore/Query/Internal/NavigationExpandingExpressionVisitor.cs

@@ -701,7 +701,7 @@ private NavigationExpansionExpression ProcessCastOfType(
                 var siblingNavigations = newEntityReference.IncludePaths.Keys
                     .Where(
                         n => !castEntityType.IsAssignableFrom(n.DeclaringEntityType)
-                            && !n.DeclaringEntityType.IsAssignableFrom(castEntityType)).ToList();
+                            && !n.DeclaringEntityType.IsAssignableFrom(castEntityType));
 
                 foreach (var navigation in siblingNavigations)
                 {