Remove build enforcement of unused usings in IDE layers

We had enabled this rule as a build time enforcement for IDE projects, but it has caused bunch of build breaks and it turning out to be too onerous to enforce. It was decided that this would be better implemented as a post-build code cleanup bot.

.editorconfig

@@ -226,9 +226,6 @@ dotnet_diagnostic.RS0037.severity = none
 dotnet_diagnostic.RS0005.severity = none
 
 [src/{Analyzers,CodeStyle,Features,Workspaces}/**/*.{cs,vb}]
-# IDE0005: Remove unnecessary usings/imports
-dotnet_diagnostic.IDE0005.severity = warning
-
 # IDE0011: Add braces
 csharp_prefer_braces = when_multiline:warning
 # NOTE: We need the below severity entry for Add Braces due to https://github.com/dotnet/roslyn/issues/44201