.editorconfig: replace invalid refactoring severity (dotnet#37367)

Valid severity levels are: `error`, `warning`, `suggestion`, `silent`, `none`

https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-language-conventions?view=vs-2019#severity-levels

.editorconfig

@@ -66,7 +66,7 @@ dotnet_naming_symbols.static_fields.applicable_kinds   = field
 dotnet_naming_symbols.static_fields.required_modifiers = static
 dotnet_naming_symbols.static_fields.applicable_accessibilities = private, internal, private_protected
 dotnet_naming_style.static_prefix_style.required_prefix = s_
-dotnet_naming_style.static_prefix_style.capitalization = camel_case 
+dotnet_naming_style.static_prefix_style.capitalization = camel_case
 
 # internal and private fields should be _camelCase
 dotnet_naming_rule.camel_case_for_private_internal_fields.severity = suggestion
@@ -75,12 +75,12 @@ dotnet_naming_rule.camel_case_for_private_internal_fields.style    = camel_case_
 dotnet_naming_symbols.private_internal_fields.applicable_kinds = field
 dotnet_naming_symbols.private_internal_fields.applicable_accessibilities = private, internal
 dotnet_naming_style.camel_case_underscore_style.required_prefix = _
-dotnet_naming_style.camel_case_underscore_style.capitalization = camel_case 
+dotnet_naming_style.camel_case_underscore_style.capitalization = camel_case
 
 # Code style defaults
 csharp_using_directive_placement = outside_namespace:suggestion
 dotnet_sort_system_directives_first = true
-csharp_prefer_braces = true:refactoring
+csharp_prefer_braces = true:silent
 csharp_preserve_single_line_blocks = true:none
 csharp_preserve_single_line_statements = false:none
 csharp_prefer_static_local_function = true:suggestion
@@ -101,19 +101,19 @@ dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggesti
 dotnet_style_prefer_inferred_tuple_names = true:suggestion
 dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
 dotnet_style_prefer_auto_properties = true:suggestion
-dotnet_style_prefer_conditional_expression_over_assignment = true:refactoring
-dotnet_style_prefer_conditional_expression_over_return = true:refactoring
+dotnet_style_prefer_conditional_expression_over_assignment = true:silent
+dotnet_style_prefer_conditional_expression_over_return = true:silent
 csharp_prefer_simple_default_expression = true:suggestion
 
 # Expression-bodied members
-csharp_style_expression_bodied_methods = true:refactoring
-csharp_style_expression_bodied_constructors = true:refactoring
-csharp_style_expression_bodied_operators = true:refactoring
-csharp_style_expression_bodied_properties = true:refactoring
-csharp_style_expression_bodied_indexers = true:refactoring
-csharp_style_expression_bodied_accessors = true:refactoring
-csharp_style_expression_bodied_lambdas = true:refactoring
-csharp_style_expression_bodied_local_functions = true:refactoring
+csharp_style_expression_bodied_methods = true:silent
+csharp_style_expression_bodied_constructors = true:silent
+csharp_style_expression_bodied_operators = true:silent
+csharp_style_expression_bodied_properties = true:silent
+csharp_style_expression_bodied_indexers = true:silent
+csharp_style_expression_bodied_accessors = true:silent
+csharp_style_expression_bodied_lambdas = true:silent
+csharp_style_expression_bodied_local_functions = true:silent
 
 # Pattern matching
 csharp_style_pattern_matching_over_is_with_cast_check = true:suggestion