Remove ICollection<TSource> check from Any() method

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/libraries/System.Linq/src/System/Linq/AnyAll.cs

@@ -15,11 +15,6 @@ public static bool Any<TSource>(this IEnumerable<TSource> source)
                 ThrowHelper.ThrowArgumentNullException(ExceptionArgument.source);
             }
 
-            if (source is ICollection<TSource> gc)
-            {
-                return gc.Count != 0;
-            }
-
             if (!IsSizeOptimized && source is Iterator<TSource> iterator)
             {
                 int count = iterator.GetCount(onlyIfCheap: true);