FIX: Remove unnecessary platforms (#2132)

Author: ritamerkl

Packages/com.unity.inputsystem/InputSystem/Editor/InputSystemPluginControl.cs

@@ -43,12 +43,6 @@ private static void CheckForExtension()
             #if UNITY_2023_3_OR_NEWER
             BuildTarget.VisionOS,
             #endif
-            #if UNITY_6000_0_OR_NEWER
-            BuildTarget.ReservedCFE,
-            #endif
-            #if UNITY_6000_0_7_OR_NEWER
-            BuildTarget.Kepler
-            #endif
             BuildTarget.NoTarget
         };