Enable IDE0071 (Simplify interpolation)

eng/CodeAnalysis.src.globalconfig

@@ -1501,7 +1501,7 @@ dotnet_diagnostic.IDE0066.severity = suggestion
 dotnet_diagnostic.IDE0070.severity = suggestion
 
 # IDE0071: Simplify interpolation
-dotnet_diagnostic.IDE0071.severity = suggestion
+dotnet_diagnostic.IDE0071.severity = warning
 
 # IDE0072: Add missing cases
 dotnet_diagnostic.IDE0072.severity = silent

src/libraries/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ComInterop/IDispatchComObject.cs

@@ -101,7 +101,7 @@ public override string ToString()
                 typeName = "IDispatch";
             }
 
-            return $"{RuntimeCallableWrapper.ToString()} ({typeName})";
+            return $"{RuntimeCallableWrapper} ({typeName})";
         }
 
         public ComTypeDesc ComTypeDesc

src/libraries/System.Drawing.Common/src/System/Drawing/Printing/PaperSize.cs

@@ -127,6 +127,6 @@ public int Width
         /// <summary>
         /// Provides some interesting information about the PaperSize in String form.
         /// </summary>
-        public override string ToString() => $"[PaperSize {PaperName} Kind={Kind.ToString()} Height={Height.ToString(CultureInfo.InvariantCulture)} Width={Width.ToString(CultureInfo.InvariantCulture)}]";
+        public override string ToString() => $"[PaperSize {PaperName} Kind={Kind} Height={Height.ToString(CultureInfo.InvariantCulture)} Width={Width.ToString(CultureInfo.InvariantCulture)}]";
     }
 }

src/libraries/System.Drawing.Common/src/System/Drawing/StringFormat.cs

@@ -437,6 +437,6 @@ internal int GetMeasurableCharacterRangeCount()
         /// <summary>
         /// Converts this <see cref='StringFormat'/> to a human-readable string.
         /// </summary>
-        public override string ToString() => $"[StringFormat, FormatFlags={FormatFlags.ToString()}]";
+        public override string ToString() => $"[StringFormat, FormatFlags={FormatFlags}]";
     }
 }

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs

@@ -1414,7 +1414,7 @@ public ValueTask<HttpResponseMessage> SendAsync(HttpRequestMessage request, bool
                 {
                     if (NetEventSource.Log.IsEnabled())
                     {
-                        Trace($"Connected with custom SslStream: alpn='${sslStream.NegotiatedApplicationProtocol.ToString()}'");
+                        Trace($"Connected with custom SslStream: alpn='${sslStream.NegotiatedApplicationProtocol}'");
                     }
                 }
                 transportContext = sslStream.TransportContext;