restore CacheOverflowTestMultithreaded as it took 67 ms and is no lon…

…ger large test only for running manually (#2953)

test/Microsoft.IdentityModel.Tokens.Tests/EventBasedLRUCacheTests.cs

@@ -359,7 +359,7 @@ internal bool IsDescending(LinkedList<LRUCacheItem<int, string>> data)
             return true;
         }
 
-        [Fact(Skip = "Large test meant to be run manually.")]
+        [Fact]
         public async Task CacheOverflowTestMultithreaded()
         {
             TestUtilities.WriteHeader($"{this}.CacheOverflowTestMultithreaded");