impl(storage): remove deprecated Client constructors (googleapis#15869)

* impl(storage): remove deprecated Client constructors

Author: mpeddada1

ci/abi-dumps/google_cloud_cpp_storage.expected.abi.dump.gz

@@ -555,6 +555,71 @@ void CreateClient() {
 
 </details>
 
+<details>
+<summary>Removed <code>Client(Connection, NoDecorations)</code> constructor</summary>
+
+The `Client` constructor that accepted a `StorageConnection` and the
+`NoDecorations` tag has been removed. This was intended only for test code.
+
+**Before:**
+
+```cpp
+#include "google/cloud/storage/client.h"
+#include "google/cloud/storage/testing/mock_storage_connection.h"
+
+void TestClient() {
+  auto mock = std::make_shared<google::cloud::storage::testing::MockStorageConnection>();
+  // ...
+  auto client = google::cloud::storage::Client(
+      mock, google::cloud::storage::Client::NoDecorations{});
+}
+```
+
+**After:**
+
+```cpp
+#include "google/cloud/storage/client.h"
+#include "google/cloud/storage/testing/mock_storage_connection.h"
+
+void TestClient() {
+  auto mock = std::make_shared<google::cloud::storage::testing::MockStorageConnection>();
+  // ...
+  auto client = google::cloud::storage::internal::ClientImplDetails::CreateWithoutDecorations(mock);
+}
+```
+
+</details>
+
+<details>
+<summary>Removed <code>Client::raw_client()</code></summary>
+
+The `Client::raw_client()` method has been removed. This was intended only for
+internal use or testing. If you need access to the underlying connection for
+testing purposes, use `google::cloud::storage::internal::ClientImplDetails`.
+
+**Before:**
+
+```cpp
+#include "google/cloud/storage/client.h"
+
+void UseRawClient(google::cloud::storage::Client client) {
+  auto connection = client.raw_client();
+}
+```
+
+**After:**
+
+```cpp
+#include "google/cloud/storage/client.h"
+
+void UseRawClient(google::cloud::storage::Client client) {
+  auto connection =
+      google::cloud::storage::internal::ClientImplDetails::GetConnection(client);
+}
+```
+
+</details>
+
 ### IAM
 
 <details>

ci/abi-dumps/google_cloud_cpp_storage_grpc.expected.abi.dump.gz

@@ -3441,27 +3441,6 @@ class Client {
   /// Define a tag to disable automatic decorations of the StorageConnection.
   struct NoDecorations {};
 
-  /// Builds a client with a specific StorageConnection, without decorations.
-  /// @deprecated This was intended only for test code, applications should not
-  /// use it.
-  GOOGLE_CLOUD_CPP_DEPRECATED(
-      "applications should not need this."
-      " Please file a bug at https://github.com/googleapis/google-cloud-cpp"
-      " if you do.")
-  explicit Client(std::shared_ptr<internal::StorageConnection> connection,
-                  NoDecorations)
-      : Client(InternalOnlyNoDecorations{}, std::move(connection)) {}
-
-  /// Access the underlying `StorageConnection`.
-  /// @deprecated Only intended for implementors, do not use.
-  GOOGLE_CLOUD_CPP_DEPRECATED(
-      "applications should not need this."
-      " Please file a bug at https://github.com/googleapis/google-cloud-cpp"
-      " if you do.")
-  std::shared_ptr<internal::StorageConnection> raw_client() const {
-    return connection_;
-  }
-
  private:
   friend class internal::NonResumableParallelUploadState;
   friend class internal::ResumableParallelUploadState;

doc/v3-migration-guide.md

@@ -117,9 +117,9 @@ TEST(GrpcPluginTest, HybridUsesGrpcBufferOptions) {
       ScopedEnvironment("GOOGLE_CLOUD_CPP_STORAGE_GRPC_CONFIG", absl::nullopt);
   auto client = MakeGrpcClient(
       TestOptions().set<storage_experimental::GrpcPluginOption>("media"));
-  EXPECT_GE(
-      client.raw_client()->options().get<storage::UploadBufferSizeOption>(),
-      32 * 1024 * 1024L);
+  auto connection = ClientImplDetails::GetConnection(client);
+  EXPECT_GE(connection->options().get<storage::UploadBufferSizeOption>(),
+            32 * 1024 * 1024UL);
 }
 
 TEST(GrpcPluginTest, BackwardsCompatibilityShims) {