don't hit disconnected servers when crawling endpoints

Author: mgravell

tests/NRedisStack.Tests/AbstractNRedisStackTest.cs

@@ -52,7 +52,7 @@ protected IDatabase GetCleanDatabase(string endpointId = EndpointsFixture.Env.St
             {
                 var server = redis.GetServer(endPoint);
 
-                if (server.IsReplica) continue;
+                if (server.IsReplica || !server.IsConnected) continue;
 
                 server.Execute("FLUSHALL");
             }

tests/NRedisStack.Tests/Search/SearchTests.cs

@@ -1514,7 +1514,7 @@ private int DatabaseSize(IDatabase db, out int replicaCount)
         var count = 0L;
         foreach (var server in db.Multiplexer.GetServers())
         {
-            if (server.IsReplica)
+            if (server.IsReplica || !server.IsConnected)
             {
                 replicaCount++;
             }
@@ -1532,7 +1532,7 @@ private async Task<int> DatabaseSizeAsync(IDatabase db)
         var count = 0L;
         foreach (var server in db.Multiplexer.GetServers())
         {
-            if (!server.IsReplica)
+            if (!server.IsReplica && server.IsConnected)
             {
                 count += await server.DatabaseSizeAsync();
             }