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.Server/Preferences/ServerPreferencesManager.cs

@@ -32,7 +32,7 @@ namespace Content.Server.Preferences
 
         // Cache player prefs on the server so we don't need as much async hell related to them.
         private readonly Dictionary<NetUserId, PlayerPrefData> _cachedPlayerPrefs =
-            new Dictionary<NetUserId, PlayerPrefData>();
+            new();
 
         private int MaxCharacterSlots => _cfg.GetCVar(CCVars.GameMaxCharacterSlots);