Use 'new' expression in places where the type is evident for content (#2590)

* Content.Client

* Content.Benchmarks

* Content.IntegrationTests

* Content.Server

* Content.Server.Database

* Content.Shared

* Content.Tests

* Merge fixes

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Shared/Administration/AdminFlagsHelper.cs

@@ -13,7 +13,7 @@ namespace Content.Shared.Administration
         // As you can tell from the boatload of bitwise ops,
         // writing this class was genuinely fun.
 
-        private static readonly Dictionary<string, AdminFlags> NameFlagsMap = new Dictionary<string, AdminFlags>();
+        private static readonly Dictionary<string, AdminFlags> NameFlagsMap = new();
         private static readonly string[] FlagsNameMap = new string[32];
 
         /// <summary>