Fix DiagnosticListener memory leak

When IsConfigured is called, it applies all services. This caused a
DiagnosticListener to get instantiated on each DbContext instantiation,
and since it wasn't disposed it caused a leak.

Fixes #15173

(cherry picked from commit 904ad9c)

src/EFCore/Infrastructure/EntityFrameworkServicesBuilder.cs

@@ -292,7 +292,7 @@ public virtual EntityFrameworkServicesBuilder TryAddCoreServices()
             TryAdd<IParameterBindingFactory, EntityTypeParameterBindingFactory>();
 
             ServiceCollectionMap
-                .TryAddSingleton<DiagnosticSource>(new DiagnosticListener(DbLoggerCategory.Name));
+                .TryAddSingleton<DiagnosticSource>(p => new DiagnosticListener(DbLoggerCategory.Name));
 
             ServiceCollectionMap.GetInfrastructure()
                 .AddDependencySingleton<DatabaseProviderDependencies>()