Remove EXPERIMENTAL API notice on C# interceptor API

src/csharp/Grpc.Core/Interceptors/CallInvokerExtensions.cs

@@ -24,7 +24,6 @@ namespace Grpc.Core.Interceptors
 {
     /// <summary>
     /// Extends the CallInvoker class to provide the interceptor facility on the client side.
-    /// This is an EXPERIMENTAL API.
     /// </summary>
     public static class CallInvokerExtensions
     {

src/csharp/Grpc.Core/Interceptors/ChannelExtensions.cs

@@ -22,7 +22,6 @@ namespace Grpc.Core.Interceptors
 {
     /// <summary>
     /// Provides extension methods to make it easy to register interceptors on Channel objects.
-    /// This is an EXPERIMENTAL API.
     /// </summary>
     public static class ChannelExtensions
     {

src/csharp/Grpc.Core/Interceptors/ClientInterceptorContext.cs

@@ -25,7 +25,6 @@ namespace Grpc.Core.Interceptors
 {
     /// <summary>
     /// Carries along the context associated with intercepted invocations on the client side.
-    /// This is an EXPERIMENTAL API.
     /// </summary>
     public struct ClientInterceptorContext<TRequest, TResponse>
         where TRequest : class

src/csharp/Grpc.Core/Interceptors/Interceptor.cs

@@ -25,7 +25,6 @@ namespace Grpc.Core.Interceptors
 {
     /// <summary>
     /// Serves as the base class for gRPC interceptors.
-    /// This is an EXPERIMENTAL API.
     /// </summary>
     public abstract class Interceptor
     {

src/csharp/Grpc.Core/Interceptors/ServerServiceDefinitionExtensions.cs

@@ -24,14 +24,12 @@ namespace Grpc.Core.Interceptors
 {
     /// <summary>
     /// Extends the ServerServiceDefinition class to add methods used to register interceptors on the server side.
-    /// This is an EXPERIMENTAL API.
     /// </summary>
     public static class ServerServiceDefinitionExtensions
     {
         /// <summary>
         /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
         /// intercepts incoming calls to the underlying service handler through the given interceptor.
-        /// This is an EXPERIMENTAL API.
         /// </summary>
         /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
         /// <param name="interceptor">The interceptor to intercept the incoming invocations with.</param>
@@ -52,7 +50,6 @@ namespace Grpc.Core.Interceptors
         /// <summary>
         /// Returns a <see cref="Grpc.Core.ServerServiceDefinition" /> instance that
         /// intercepts incoming calls to the underlying service handler through the given interceptors.
-        /// This is an EXPERIMENTAL API.
         /// </summary>
         /// <param name="serverServiceDefinition">The <see cref="Grpc.Core.ServerServiceDefinition" /> instance to register interceptors on.</param>
         /// <param name="interceptors">