Bump editorconfig csharp_prefer_braces down to suggestion (#21041)

So our dotnet format run will not try to fix all the braces over night.

.editorconfig

@@ -106,7 +106,7 @@ dotnet_naming_style.camel_case_underscore_style.capitalization = camel_case
 dotnet_sort_system_directives_first = true
 csharp_preserve_single_line_blocks = true
 csharp_preserve_single_line_statements = false
-csharp_prefer_braces = true:error
+csharp_prefer_braces = true:suggestion
 
 # Expression-level preferences
 dotnet_style_object_initializer = true:suggestion