Cleanup unused namespaces across multiple files

Removed several unnecessary `using` directives, including
`System.Linq`, `System.Threading.Tasks`, and others, to
streamline code and improve readability. Made minor
formatting adjustments in `SubscriberClass.cs` and
refactored dependencies in `CAP.BuilderTest.cs` and
`TestServiceCollectionExtensions.cs`. Overall, these
changes enhance code maintainability by reducing
unneeded dependencies.

Author: yang-xiaodong

src/DotNetCore.CAP.MySql/ICapTransaction.MySql.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Core Community. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-using System;
 using System.Data;
 using System.Data.Common;
 using System.Diagnostics;

src/DotNetCore.CAP.MySql/IDataStorage.MySql.cs

@@ -5,7 +5,6 @@
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using DotNetCore.CAP.Internal;

src/DotNetCore.CAP.PostgreSql/ICapTransaction.PostgreSql.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Core Community. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-using System;
 using System.Data;
 using System.Data.Common;
 using System.Diagnostics;

src/DotNetCore.CAP.PostgreSql/IDataStorage.PostgreSql.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Data.Common;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using DotNetCore.CAP.Internal;

src/DotNetCore.CAP.SqlServer/IDataStorage.SqlServer.cs

@@ -5,7 +5,6 @@
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using DotNetCore.CAP.Internal;

src/DotNetCore.CAP/Internal/ISubscribeExector.Default.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Net;
 using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;

test/DotNetCore.CAP.MultiModuleSubscriberTests/SubscriberClass.cs

@@ -1,6 +1,4 @@
-using System;
-
-namespace DotNetCore.CAP.MultiModuleSubscriberTests
+namespace DotNetCore.CAP.MultiModuleSubscriberTests
 {
     public class SubscriberClass
     {

test/DotNetCore.CAP.Test/CAP.BuilderTest.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
-using DotNetCore.CAP.Internal;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Xunit;

test/DotNetCore.CAP.Test/Helpers/ObservableCollectionExtensions.cs

@@ -5,7 +5,6 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Xunit;
 
 namespace DotNetCore.CAP.Test.Helpers
 {

test/DotNetCore.CAP.Test/Helpers/TestServiceCollectionExtensions.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Threading;
+using System.Threading;
 using DotNetCore.CAP.Test.FakeInMemoryQueue;
 using Microsoft.Extensions.DependencyInjection;
 using Xunit.Abstractions;