Further integration test modifications

- Don't use .Count() in polling; materialize the list to avoid duplicate RPCs
- Remove 10 minute somewhat-pointless no-exception test

apis/Google.Cloud.Diagnostics.AspNetCore/Google.Cloud.Diagnostics.AspNetCore.IntegrationTests/ErrorReporting/ErrorReportingTest.cs

@@ -46,17 +46,6 @@ public ErrorReportingTest()
             _client = _server.CreateClient();
         }
 
-        [Fact]
-        public async Task NoExceptions()
-        {
-            var response = await _client.GetAsync($"/ErrorReporting/{nameof(ErrorReportingController.Index)}/{_testId}");
-
-            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
-
-            var errorEvents = s_polling.GetEvents(_testId, 0);
-            Assert.Empty(errorEvents);
-        }
-
         [Fact]
         public async Task ManualLog()
         {

apis/Google.Cloud.Diagnostics.Common/Google.Cloud.Diagnostics.Common.IntegrationTests/BaseEntryPolling.cs

@@ -62,13 +62,16 @@ protected IEnumerable<T> GetEntries(int minEntries, Func<IEnumerable<T>> getEntr
                 totalSleepTime += sleepTime;
                 Thread.Sleep(sleepTime);
 
-                IEnumerable<T> entries = getEntries();
-                if (minEntries == 0 || entries.Count() >= minEntries)
+                List<T> entries = getEntries().ToList();
+                if (entries.Count >= minEntries)
                 {
                     return entries;
                 }
             }
-            return new List<T>();
+            // We don't throw an exception here, as even if we've been asked for some entries, it may be that
+            // we're in a situation of expecting at least one of a few polls to succeed, and we just wanted to
+            // try hard to find it.
+            return Enumerable.Empty<T>();
         }
     }
 }