catchunks: increase retx limit and improve statistics

Increased the retx limit from 3 to 15 (default in Linux TCP).
Added statistics about skipped retransmission.
Cleaned up statistic output.

Change-Id: I66ce9ac9fa08f7492f84bec48b7464ddb1228ab1
refs: #4861 #4603
diff --git a/tests/chunks/discover-version-realtime.t.cpp b/tests/chunks/discover-version-realtime.t.cpp
index 630594b..5bfcfce 100644
--- a/tests/chunks/discover-version-realtime.t.cpp
+++ b/tests/chunks/discover-version-realtime.t.cpp
@@ -58,7 +58,7 @@
   {
     Options options;
     options.isVerbose = false;
-    options.maxRetriesOnTimeoutOrNack = 3;
+    options.maxRetriesOnTimeoutOrNack = 15;
     return options;
   }
 };